<?xml version="1.0" encoding="us-ascii"?>
<!-- DFIN ActiveDisclosure(SM) XBRL Schema Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date      : 2020-11-09T22:28:07.2376344+00:00 -->
<!-- Version            : 5.0.1.513 -->
<!-- Package ID         : 386db0cf5af0445ea17b5b5a997e19d0 -->
<!-- Copyright (c) 2020 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
<xsd:schema xmlns:nonnum="http://www.xbrl.org/dtr/type/non-numeric" xmlns:num="http://www.xbrl.org/dtr/type/numeric" xmlns:sic="http://xbrl.sec.gov/sic/2011-01-31" xmlns:stpr="http://xbrl.sec.gov/stpr/2018-01-31" xmlns:naics="http://xbrl.sec.gov/naics/2017-01-31" xmlns:srt-types="http://fasb.org/srt-types/2019-01-31" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:srt="http://fasb.org/srt/2019-01-31" xmlns:us-gaap="http://fasb.org/us-gaap/2019-01-31" xmlns:dei="http://xbrl.sec.gov/dei/2019-01-31" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:country="http://xbrl.sec.gov/country/2017-01-31" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:currency="http://xbrl.sec.gov/currency/2019-01-31" xmlns:us-types="http://fasb.org/us-types/2019-01-31" xmlns:beam="http://www.beamtx.com/20200930" xmlns:exch="http://xbrl.sec.gov/exch/2019-01-31" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.beamtx.com/20200930" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/instance" />
  <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/linkbase" />
  <xsd:import schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" namespace="http://xbrl.org/2005/xbrldt" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd" namespace="http://xbrl.sec.gov/country/2017-01-31" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/currency/2019/currency-2019-01-31.xsd" namespace="http://xbrl.sec.gov/currency/2019-01-31" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/dei/2019/dei-2019-01-31.xsd" namespace="http://xbrl.sec.gov/dei/2019-01-31" />
  <xsd:import schemaLocation="http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd" namespace="http://www.xbrl.org/dtr/type/non-numeric" />
  <xsd:import schemaLocation="http://www.xbrl.org/dtr/type/numeric-2009-12-16.xsd" namespace="http://www.xbrl.org/dtr/type/numeric" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/exch/2019/exch-2019-01-31.xsd" namespace="http://xbrl.sec.gov/exch/2019-01-31" />
  <xsd:import schemaLocation="http://www.xbrl.org/lrr/arcrole/factExplanatory-2009-12-16.xsd" namespace="http://www.xbrl.org/2009/arcrole/fact-explanatoryFact" />
  <xsd:import schemaLocation="http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd" namespace="http://www.xbrl.org/2009/role/negated" />
  <xsd:import schemaLocation="http://www.xbrl.org/lrr/role/net-2009-12-16.xsd" namespace="http://www.xbrl.org/2009/role/net" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/naics/2017/naics-2017-01-31.xsd" namespace="http://xbrl.sec.gov/naics/2017-01-31" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/sic/2011/sic-2011-01-31.xsd" namespace="http://xbrl.sec.gov/sic/2011-01-31" />
  <xsd:import schemaLocation="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd" namespace="http://fasb.org/srt/2019-01-31" />
  <xsd:import schemaLocation="http://xbrl.fasb.org/srt/2019/elts/srt-roles-2019-01-31.xsd" namespace="http://fasb.org/srt-roles/2019-01-31" />
  <xsd:import schemaLocation="http://xbrl.fasb.org/srt/2019/elts/srt-types-2019-01-31.xsd" namespace="http://fasb.org/srt-types/2019-01-31" />
  <xsd:import schemaLocation="https://xbrl.sec.gov/stpr/2018/stpr-2018-01-31.xsd" namespace="http://xbrl.sec.gov/stpr/2018-01-31" />
  <xsd:import schemaLocation="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd" namespace="http://fasb.org/us-gaap/2019-01-31" />
  <xsd:import schemaLocation="http://xbrl.fasb.org/us-gaap/2019/elts/us-roles-2019-01-31.xsd" namespace="http://fasb.org/us-roles/2019-01-31" />
  <xsd:import schemaLocation="http://xbrl.fasb.org/us-gaap/2019/elts/us-types-2019-01-31.xsd" namespace="http://fasb.org/us-types/2019-01-31" />
  <xsd:annotation>
    <xsd:appinfo>
      <link:roleType id="TemplateLink" roleURI="http://www.beamtx.com/20200930/role/TemplateLink" xmlns:link="http://www.xbrl.org/2003/linkbase">
        <link:definition>00000 - Document - Template Link</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="beam-20200930_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:title="Calculation Links, all" xlink:type="simple" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="beam-20200930_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:title="Definition Links, all" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="beam-20200930_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:title="Label Links, all" xlink:type="simple" />
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="beam-20200930_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:title="Presentation Links, all" xlink:type="simple" />
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DocumentDocumentAndEntityInformation" id="Role_DocumentDocumentAndEntityInformation">
        <link:definition>100000 - Document - Document and Entity Information</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited" id="Role_StatementCondensedConsolidatedBalanceSheetsUnaudited">
        <link:definition>100010 - Statement - Condensed Consolidated Balance Sheets (Unaudited)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited" id="Role_StatementCondensedConsolidatedBalanceSheetsParentheticalUnaudited">
        <link:definition>100020 - Statement - Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsAndOtherComprehensiveLossUnaudited" id="Role_StatementCondensedConsolidatedStatementsOfOperationsAndOtherComprehensiveLossUnaudited">
        <link:definition>100030 - Statement - Condensed Consolidated Statements of Operations and Other Comprehensive Loss (Unaudited)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/StatementCondensedConsolidatedStatementsOfRedeemableConvertiblePreferredStockAndStockholdersEquityDeficitUnaudited" id="Role_StatementCondensedConsolidatedStatementsOfRedeemableConvertiblePreferredStockAndStockholdersEquityDeficitUnaudited">
        <link:definition>100040 - Statement - Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders&apos; Equity (Deficit) (Unaudited)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/StatementCondensedConsolidatedStatementsOfRedeemableConvertiblePreferredStockAndStockholdersEquityDeficitUnauditedParenthetical" id="Role_StatementCondensedConsolidatedStatementsOfRedeemableConvertiblePreferredStockAndStockholdersEquityDeficitUnauditedParenthetical">
        <link:definition>100050 - Statement - Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders&apos; Equity (Deficit) (Unaudited) (Parenthetical)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited" id="Role_StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited">
        <link:definition>100060 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureNatureOfBusinessAndBasisOfPresentation" id="Role_DisclosureNatureOfBusinessAndBasisOfPresentation">
        <link:definition>100070 - Disclosure - Nature of the Business and Basis of Presentation</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureSummaryOfSignificantAccountingPolicies" id="Role_DisclosureSummaryOfSignificantAccountingPolicies">
        <link:definition>100080 - Disclosure - Summary of Significant Accounting Policies</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosurePropertyAndEquipmentNet" id="Role_DisclosurePropertyAndEquipmentNet">
        <link:definition>100090 - Disclosure - Property and Equipment, Net</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureFairValueOfFinancialInstruments" id="Role_DisclosureFairValueOfFinancialInstruments">
        <link:definition>100100 - Disclosure - Fair Value of Financial Instruments</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureMarketableSecurities" id="Role_DisclosureMarketableSecurities">
        <link:definition>100110 - Disclosure - Marketable Securities</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureAccruedExpensesAndOtherCurrentLiabilities" id="Role_DisclosureAccruedExpensesAndOtherCurrentLiabilities">
        <link:definition>100120 - Disclosure - Accrued Expenses and Other Current Liabilities</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLeases" id="Role_DisclosureLeases">
        <link:definition>100130 - Disclosure - Leases</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLicenseAgreements" id="Role_DisclosureLicenseAgreements">
        <link:definition>100140 - Disclosure - License Agreements</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureCollaborationAndLicenseAgreements" id="Role_DisclosureCollaborationAndLicenseAgreements">
        <link:definition>100150 - Disclosure - Collaboration and License Agreements</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosurePreferredAndCommonStock" id="Role_DisclosurePreferredAndCommonStock">
        <link:definition>100160 - Disclosure - Preferred and Common Stock</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureStockOptionAndGrantPlan" id="Role_DisclosureStockOptionAndGrantPlan">
        <link:definition>100170 - Disclosure - Stock Option and Grant Plan</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureNetLossPerShareAttributableToCommonStockholders" id="Role_DisclosureNetLossPerShareAttributableToCommonStockholders">
        <link:definition>100180 - Disclosure - Net Loss per Share Attributable to Common Stockholders</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureIncomeTaxes" id="Role_DisclosureIncomeTaxes">
        <link:definition>100190 - Disclosure - Income Taxes</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureRelatedPartyTransactions" id="Role_DisclosureRelatedPartyTransactions">
        <link:definition>100200 - Disclosure - Related Party Transactions</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies" id="Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies">
        <link:definition>100210 - Disclosure - Summary of Significant Accounting Policies (Policies)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesTables" id="Role_DisclosureSummaryOfSignificantAccountingPoliciesTables">
        <link:definition>100220 - Disclosure - Summary of Significant Accounting Policies (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosurePropertyAndEquipmentNetTables" id="Role_DisclosurePropertyAndEquipmentNetTables">
        <link:definition>100230 - Disclosure - Property and Equipment, Net (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsTables" id="Role_DisclosureFairValueOfFinancialInstrumentsTables">
        <link:definition>100240 - Disclosure - Fair Value of Financial Instruments (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureMarketableSecuritiesTables" id="Role_DisclosureMarketableSecuritiesTables">
        <link:definition>100250 - Disclosure - Marketable Securities (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureAccruedExpensesAndOtherCurrentLiabilitiesTables" id="Role_DisclosureAccruedExpensesAndOtherCurrentLiabilitiesTables">
        <link:definition>100260 - Disclosure - Accrued Expenses and Other Current Liabilities (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLeasesTables" id="Role_DisclosureLeasesTables">
        <link:definition>100270 - Disclosure - Leases (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLicenseAgreementsTables" id="Role_DisclosureLicenseAgreementsTables">
        <link:definition>100280 - Disclosure - License Agreements (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureStockOptionAndGrantPlanTables" id="Role_DisclosureStockOptionAndGrantPlanTables">
        <link:definition>100290 - Disclosure - Stock Option and Grant Plan (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureNetLossPerShareAttributableToCommonStockholdersTables" id="Role_DisclosureNetLossPerShareAttributableToCommonStockholdersTables">
        <link:definition>100300 - Disclosure - Net Loss per Share Attributable to Common Stockholders (Tables)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureNatureOfBusinessAndBasisOfPresentationAdditionalInformationDetails" id="Role_DisclosureNatureOfBusinessAndBasisOfPresentationAdditionalInformationDetails">
        <link:definition>100310 - Disclosure - Nature of the Business and Basis of Presentation - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureSummaryOfSignificantAccountingPoliciesReconciliationOfCashCashEquivalentsAndRestrictedCashDetails" id="Role_DisclosureSummaryOfSignificantAccountingPoliciesReconciliationOfCashCashEquivalentsAndRestrictedCashDetails">
        <link:definition>100320 - Disclosure - Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosurePropertyAndEquipmentNetScheduleOfPropertyAndEquipmentDetails" id="Role_DisclosurePropertyAndEquipmentNetScheduleOfPropertyAndEquipmentDetails">
        <link:definition>100330 - Disclosure - Property and Equipment, Net - Schedule of Property and Equipment (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosurePropertyAndEquipmentNetSummaryOfDepreciationExpenseIncurredDetails" id="Role_DisclosurePropertyAndEquipmentNetSummaryOfDepreciationExpenseIncurredDetails">
        <link:definition>100340 - Disclosure - Property and Equipment, Net - Summary of Depreciation Expense Incurred (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsAdditionalInformationDetails" id="Role_DisclosureFairValueOfFinancialInstrumentsAdditionalInformationDetails">
        <link:definition>100350 - Disclosure - Fair Value of Financial Instruments - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsScheduleOfFairValueOfFinancialAssetsAndLiabilitiesDetails" id="Role_DisclosureFairValueOfFinancialInstrumentsScheduleOfFairValueOfFinancialAssetsAndLiabilitiesDetails">
        <link:definition>100360 - Disclosure - Fair Value of Financial Instruments - Schedule of Fair Value of Financial Assets and Liabilities (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsScheduleOfCalculationOfEstimatedFairValueOfSuccessPaymentLiabilitiesDetails" id="Role_DisclosureFairValueOfFinancialInstrumentsScheduleOfCalculationOfEstimatedFairValueOfSuccessPaymentLiabilitiesDetails">
        <link:definition>100370 - Disclosure - Fair Value of Financial Instruments - Schedule of Calculation of Estimated Fair Value of Success Payment Liabilities (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsScheduleOfCalculationOfEstimatedFairValueOfSuccessPaymentLiabilitiesParentheticalDetails" id="Role_DisclosureFairValueOfFinancialInstrumentsScheduleOfCalculationOfEstimatedFairValueOfSuccessPaymentLiabilitiesParentheticalDetails">
        <link:definition>100380 - Disclosure - Fair Value of Financial Instruments - Schedule of Calculation of Estimated Fair Value of Success Payment Liabilities (Parenthetical) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureFairValueOfFinancialInstrumentsScheduleOfChangeInFairValueOfSuccessPaymentLiabilitiesBasedOnLevel3InputsDetails" id="Role_DisclosureFairValueOfFinancialInstrumentsScheduleOfChangeInFairValueOfSuccessPaymentLiabilitiesBasedOnLevel3InputsDetails">
        <link:definition>100390 - Disclosure - Fair Value of Financial Instruments - Schedule of Change in Fair Value of Success Payment Liabilities Based on Level 3 Inputs (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureMarketableSecuritiesSummaryOfMarketableSecuritiesHeldDetails" id="Role_DisclosureMarketableSecuritiesSummaryOfMarketableSecuritiesHeldDetails">
        <link:definition>100400 - Disclosure - Marketable Securities - Summary of Marketable Securities Held (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureMarketableSecuritiesAdditionalInformationDetails" id="Role_DisclosureMarketableSecuritiesAdditionalInformationDetails">
        <link:definition>100410 - Disclosure - Marketable Securities - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureAccruedExpensesAndOtherCurrentLiabilitiesScheduleOfAccruedExpensesAndOtherCurrentLiabilitiesDetails" id="Role_DisclosureAccruedExpensesAndOtherCurrentLiabilitiesScheduleOfAccruedExpensesAndOtherCurrentLiabilitiesDetails">
        <link:definition>100420 - Disclosure - Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureAccruedExpensesAndOtherCurrentLiabilitiesScheduleOfAccruedExpensesAndOtherCurrentLiabilitiesParentheticalDetails" id="Role_DisclosureAccruedExpensesAndOtherCurrentLiabilitiesScheduleOfAccruedExpensesAndOtherCurrentLiabilitiesParentheticalDetails">
        <link:definition>100430 - Disclosure - Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Parenthetical) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLeasesAdditionalInformationDetails" id="Role_DisclosureLeasesAdditionalInformationDetails">
        <link:definition>100440 - Disclosure - Leases - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLeasesSummaryOfOperatingLeaseCostsDetails" id="Role_DisclosureLeasesSummaryOfOperatingLeaseCostsDetails">
        <link:definition>100450 - Disclosure - Leases - Summary of Operating Lease Costs (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLeasesSummaryOfLeaseTermAndDiscountRateDetails" id="Role_DisclosureLeasesSummaryOfLeaseTermAndDiscountRateDetails">
        <link:definition>100460 - Disclosure - Leases - Summary of Lease Term and Discount Rate (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLeasesSummaryOfCashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesDetails" id="Role_DisclosureLeasesSummaryOfCashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesDetails">
        <link:definition>100470 - Disclosure - Leases - Summary of Cash Paid for Amounts Included in Measurement of Lease Liabilities (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLeasesSummaryOfFutureMinimumLeasePaymentsOfOperatingLeasesDetails" id="Role_DisclosureLeasesSummaryOfFutureMinimumLeasePaymentsOfOperatingLeasesDetails">
        <link:definition>100480 - Disclosure - Leases - Summary of Future Minimum Lease Payments of Operating Leases (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLeasesSummaryOfFutureMinimumLeasePaymentsOfOperatingLeasesDetails2" id="Role_DisclosureLeasesSummaryOfFutureMinimumLeasePaymentsOfOperatingLeasesDetails2">
        <link:definition>100490 - Disclosure - Leases - Summary of Future Minimum Lease Payments of Operating Leases (Details)2</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLeasesSummaryOfFutureMinimumPaymentsRelatedToEquipmentFinancingObligationsDetails" id="Role_DisclosureLeasesSummaryOfFutureMinimumPaymentsRelatedToEquipmentFinancingObligationsDetails">
        <link:definition>100500 - Disclosure - Leases - Summary of Future Minimum Payments Related to Equipment Financing Obligations (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLeasesSummaryOfFutureMinimumPaymentsRelatedToEquipmentFinancingObligationsDetails2" id="Role_DisclosureLeasesSummaryOfFutureMinimumPaymentsRelatedToEquipmentFinancingObligationsDetails2">
        <link:definition>100510 - Disclosure - Leases - Summary of Future Minimum Payments Related to Equipment Financing Obligations (Details)2</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLeasesSummaryOfFutureMinimumPaymentsRelatedToEquipmentFinancingObligationsParentheticalDetails" id="Role_DisclosureLeasesSummaryOfFutureMinimumPaymentsRelatedToEquipmentFinancingObligationsParentheticalDetails">
        <link:definition>100520 - Disclosure - Leases - Summary of Future Minimum Payments Related to Equipment Financing Obligations (Parenthetical) (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLeasesSummaryOfPrincipalAndInterestPortionsDetails" id="Role_DisclosureLeasesSummaryOfPrincipalAndInterestPortionsDetails">
        <link:definition>100530 - Disclosure - Leases - Summary of Principal and Interest Portions (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLicenseAgreementsHarvardLicenseAgreementAdditionalInformationDetails" id="Role_DisclosureLicenseAgreementsHarvardLicenseAgreementAdditionalInformationDetails">
        <link:definition>100540 - Disclosure - License Agreements - Harvard License Agreement - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLicenseAgreementsHarvardLicenseAgreementSuccessPaymentLiabilityDetails" id="Role_DisclosureLicenseAgreementsHarvardLicenseAgreementSuccessPaymentLiabilityDetails">
        <link:definition>100550 - Disclosure - License Agreements - Harvard License Agreement - Success Payment Liability (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLicenseAgreementsHarvardLicenseAgreementChangeInFairValueOfSuccessPaymentLiabilityDetails" id="Role_DisclosureLicenseAgreementsHarvardLicenseAgreementChangeInFairValueOfSuccessPaymentLiabilityDetails">
        <link:definition>100560 - Disclosure - License Agreements - Harvard License Agreement - Change in Fair Value of Success Payment Liability (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLicenseAgreementsBroadLicenseAgreementAdditionalInformationDetails" id="Role_DisclosureLicenseAgreementsBroadLicenseAgreementAdditionalInformationDetails">
        <link:definition>100570 - Disclosure - License Agreements - Broad License Agreement - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLicenseAgreementsBroadLicenseAgreementSuccessPaymentLiabilityDetails" id="Role_DisclosureLicenseAgreementsBroadLicenseAgreementSuccessPaymentLiabilityDetails">
        <link:definition>100580 - Disclosure - License Agreements - Broad License Agreement - Success Payment Liability (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLicenseAgreementsBroadLicenseAgreementChangeInFairValueOfSuccessPaymentLiabilityDetails" id="Role_DisclosureLicenseAgreementsBroadLicenseAgreementChangeInFairValueOfSuccessPaymentLiabilityDetails">
        <link:definition>100590 - Disclosure - License Agreements - Broad License Agreement - Change in Fair Value of Success Payment Liability (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLicenseAgreementsEditasLicenseAgreementAdditionalInformationDetails" id="Role_DisclosureLicenseAgreementsEditasLicenseAgreementAdditionalInformationDetails">
        <link:definition>100600 - Disclosure - License Agreements - Editas License Agreement - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureLicenseAgreementsBioPaletteAdditionalInformationDetails" id="Role_DisclosureLicenseAgreementsBioPaletteAdditionalInformationDetails">
        <link:definition>100610 - Disclosure - License Agreements - Bio Palette - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureCollaborationAndLicenseAgreementsAdditionalInformationDetails" id="Role_DisclosureCollaborationAndLicenseAgreementsAdditionalInformationDetails">
        <link:definition>100620 - Disclosure - Collaboration and License Agreements - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosurePreferredAndCommonStockAdditionalInformationDetails" id="Role_DisclosurePreferredAndCommonStockAdditionalInformationDetails">
        <link:definition>100630 - Disclosure - Preferred and Common Stock - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureStockOptionAndGrantPlanAdditionalInformationDetails" id="Role_DisclosureStockOptionAndGrantPlanAdditionalInformationDetails">
        <link:definition>100640 - Disclosure - Stock Option and Grant Plan - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureStockOptionAndGrantPlanSummaryOfStockBasedCompensationExpenseDetails" id="Role_DisclosureStockOptionAndGrantPlanSummaryOfStockBasedCompensationExpenseDetails">
        <link:definition>100650 - Disclosure - Stock Option and Grant Plan - Summary of Stock-based Compensation Expense (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureStockOptionAndGrantPlanSummaryOfOptionActivityUnderEquityAwardPlansDetails" id="Role_DisclosureStockOptionAndGrantPlanSummaryOfOptionActivityUnderEquityAwardPlansDetails">
        <link:definition>100660 - Disclosure - Stock Option and Grant Plan - Summary of Option Activity Under Equity Award Plans (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureStockOptionAndGrantPlanSummaryOfRestrictedStockActivityDetails" id="Role_DisclosureStockOptionAndGrantPlanSummaryOfRestrictedStockActivityDetails">
        <link:definition>100670 - Disclosure - Stock Option and Grant Plan - Summary of Restricted Stock Activity (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureNetLossPerShareAttributableToCommonStockholdersScheduleOfPotentialCommonSharesExcludedFromComputationOfDilutedNetLossPerShareDetails" id="Role_DisclosureNetLossPerShareAttributableToCommonStockholdersScheduleOfPotentialCommonSharesExcludedFromComputationOfDilutedNetLossPerShareDetails">
        <link:definition>100680 - Disclosure - Net Loss per Share Attributable to Common Stockholders - Schedule of Potential Common Shares Excluded from Computation of Diluted Net Loss per Share (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureNetLossPerShareAttributableToCommonStockholdersSummaryOfComputationOfBasicAndDilutedNetLossPerShareAttributableToCommonStockholdersDetails" id="Role_DisclosureNetLossPerShareAttributableToCommonStockholdersSummaryOfComputationOfBasicAndDilutedNetLossPerShareAttributableToCommonStockholdersDetails">
        <link:definition>100690 - Disclosure - Net Loss per Share Attributable to Common Stockholders - Summary of Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureNetLossPerShareAttributableToCommonStockholdersAdditionalInformationDetails" id="Role_DisclosureNetLossPerShareAttributableToCommonStockholdersAdditionalInformationDetails">
        <link:definition>100700 - Disclosure - Net Loss per Share Attributable to Common Stockholders - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.beamtx.com/20200930/taxonomy/role/DisclosureRelatedPartyTransactionsAdditionalInformationDetails" id="Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails">
        <link:definition>100710 - Disclosure - Related Party Transactions - Additional Information (Details)</link:definition>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xsd:appinfo>
  </xsd:annotation>
  <xsd:element id="beam_LesseeOperatingLeaseLiabilityPaymentsDueYearSix" name="LesseeOperatingLeaseLiabilityPaymentsDueYearSix" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearSix" name="LesseeOperatingLeaseLiabilityPaymentsDueAfterYearSix" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_FinanceLeaseLiabilityResidualValues" name="FinanceLeaseLiabilityResidualValues" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_AccruedExpensesAndOtherCurrentLiabilities" name="AccruedExpensesAndOtherCurrentLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_InterestAndOtherIncomeExpenseNet" name="InterestAndOtherIncomeExpenseNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_AvailableForSaleSecuritiesTransferredSecurityUnrealizedGainLoss" name="AvailableForSaleSecuritiesTransferredSecurityUnrealizedGainLoss" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_OtherOperatingIncomeExpenseAbstract" name="OtherOperatingIncomeExpenseAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_ReconciliationOfNetGainLossToNetLossAttributableToCommonStockholdersAbstract" name="ReconciliationOfNetGainLossToNetLossAttributableToCommonStockholdersAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues" name="TemporaryEquityStockIssuedDuringPeriodSharesNewIssues" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_AccretionOfRedeemableConvertiblePreferredStockToRedemptionValue" name="AccretionOfRedeemableConvertiblePreferredStockToRedemptionValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_TemporaryEquityConversionOfRedeemableConvertiblePreferredStockToCommonStockUponClosingOfInitialPublicOfferingValue" name="TemporaryEquityConversionOfRedeemableConvertiblePreferredStockToCommonStockUponClosingOfInitialPublicOfferingValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_StockIssuedDuringPeriodValueVestingOfRestrictedCommonStock" name="StockIssuedDuringPeriodValueVestingOfRestrictedCommonStock" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_IssuanceOfCommonStockValueRelatedToLicenseAgreement" name="IssuanceOfCommonStockValueRelatedToLicenseAgreement" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_TemporaryEquityConversionOfRedeemableConvertiblePreferredStockToCommonStockUponClosingOfInitialPublicOfferingShares" name="TemporaryEquityConversionOfRedeemableConvertiblePreferredStockToCommonStockUponClosingOfInitialPublicOfferingShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_StockIssuedDuringPeriodSharesVestingOfRestrictedCommonStock" name="StockIssuedDuringPeriodSharesVestingOfRestrictedCommonStock" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_IssuanceOfCommonStockSharesRelatedToLicenseAgreement" name="IssuanceOfCommonStockSharesRelatedToLicenseAgreement" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_TemporaryEquityNetIssuanceCost" name="TemporaryEquityNetIssuanceCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_SeriesBRedeemableConvertiblePreferredStockMember" name="SeriesBRedeemableConvertiblePreferredStockMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_InitialPublicOfferingNetOfIssuanceCosts" name="InitialPublicOfferingNetOfIssuanceCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_ChangeInOperatingLeaseRightOfUseAssets" name="ChangeInOperatingLeaseRightOfUseAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_NonCashResearchAndDevelopmentLicenseExpenseNet" name="NonCashResearchAndDevelopmentLicenseExpenseNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_ChangeInFairValueOfDerivativeLiabilities" name="ChangeInFairValueOfDerivativeLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_IncreaseDecreaseInOperatingLeaseLiabilities" name="IncreaseDecreaseInOperatingLeaseLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_IncreaseDecreaseInFinancingMilestoneLiabilities" name="IncreaseDecreaseInFinancingMilestoneLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_ProceedsFromEquipmentFinancings" name="ProceedsFromEquipmentFinancings" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_RepaymentOfEquipmentFinancings" name="RepaymentOfEquipmentFinancings" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_ReceiptOfCommonStockInExchangeForTechnologyLicense" name="ReceiptOfCommonStockInExchangeForTechnologyLicense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_EquityIssuanceCostsInAccountsPayableAndAccruedExpenses" name="EquityIssuanceCostsInAccountsPayableAndAccruedExpenses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_LeasesDisclosureTextBlock" name="LeasesDisclosureTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_LicenseAgreementDisclosureTextBlock" name="LicenseAgreementDisclosureTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_SummaryOfDepreciationExpenseIncurredTableTextBlock" name="SummaryOfDepreciationExpenseIncurredTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisSuccessPaymentDerivativeLiabilitiesTableTextBlock" name="FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisSuccessPaymentDerivativeLiabilitiesTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_ScheduleOfAccruedExpensesAndOtherCurrentLiabilitiesTableTextBlock" name="ScheduleOfAccruedExpensesAndOtherCurrentLiabilitiesTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_SummaryOfLeaseTermAndDiscountRateTableTextBlock" name="SummaryOfLeaseTermAndDiscountRateTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_SummaryOfCashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesTableTextBlock" name="SummaryOfCashPaidForAmountsIncludedInMeasurementOfLeaseLiabilitiesTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_SummaryOfPrincipalAndInterestPortionsTableTextBlock" name="SummaryOfPrincipalAndInterestPortionsTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_ScheduleOfSuccessPaymentLiabilityTableTextBlock" name="ScheduleOfSuccessPaymentLiabilityTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_ScheduleOfChangeInFairValueOfSuccessPaymentLiabilityTableTextBlock" name="ScheduleOfChangeInFairValueOfSuccessPaymentLiabilityTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_NatureOfBusinessAndBasisOfPresentationLineItems" name="NatureOfBusinessAndBasisOfPresentationLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_NatureOfBusinessAndBasisOfPresentationTable" name="NatureOfBusinessAndBasisOfPresentationTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_LabEquipmentMember" name="LabEquipmentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_InterestAndOtherIncomeExpenseMember" name="InterestAndOtherIncomeExpenseMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_HarvardLicenseAgreementMember" name="HarvardLicenseAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_BroadLicenseAgreementMember" name="BroadLicenseAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_MeasurementInputFairValueOfPreferredStockMember" name="MeasurementInputFairValueOfPreferredStockMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_MeasurementInputFairValueOfCommonStockMember" name="MeasurementInputFairValueOfCommonStockMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_FairValueOfPreferredStockPricePerShareAfterAdjustedReverseStockSplit" name="FairValueOfPreferredStockPricePerShareAfterAdjustedReverseStockSplit" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="beam_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisSuccessPaymentLiabilityPeriodIncreaseDecrease" name="FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisSuccessPaymentLiabilityPeriodIncreaseDecrease" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisSuccessPaymentLiabilityValue" name="FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisSuccessPaymentLiabilityValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_AccruedLicenseCosts" name="AccruedLicenseCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_AccruedProcessDevelopmentAndManufacturingCosts" name="AccruedProcessDevelopmentAndManufacturingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_AccruedOtherResearchCosts" name="AccruedOtherResearchCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_OtherAccruedExpensesAndOtherCurrentLiabilities" name="OtherAccruedExpensesAndOtherCurrentLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_OperatingLeaseCommencementMonthAndYear" name="OperatingLeaseCommencementMonthAndYear" type="xbrli:gYearMonthItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_OperatingLeaseTerminationMonthAndYear" name="OperatingLeaseTerminationMonthAndYear" type="xbrli:gYearMonthItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_OfficeAndLaboratorySpaceMember" name="OfficeAndLaboratorySpaceMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_LaboratorySpaceMember" name="LaboratorySpaceMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_AlexandriaRealEstateEquitiesIncMember" name="AlexandriaRealEstateEquitiesIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_OperatingLeaseAmendmentMonthAndYear" name="OperatingLeaseAmendmentMonthAndYear" type="xbrli:gYearMonthItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_LesseeOperatingLeaseLeaseNotYetCommencedExpirationTerm" name="LesseeOperatingLeaseLeaseNotYetCommencedExpirationTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_LesseeOperatingLeaseLeaseNotYetCommencedTenantImprovement" name="LesseeOperatingLeaseLeaseNotYetCommencedTenantImprovement" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_LesseeOperatingLeaseLeaseNotYetCommencedSecurityDeposit" name="LesseeOperatingLeaseLeaseNotYetCommencedSecurityDeposit" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_LesseeOperatingLeaseLeaseNotYetCommencedAnticipatedUndiscountedLeasePaymentsDue" name="LesseeOperatingLeaseLeaseNotYetCommencedAnticipatedUndiscountedLeasePaymentsDue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_ManufacturingFacilityNumberOfSquareFeet" name="ManufacturingFacilityNumberOfSquareFeet" type="num:areaItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_NumberOfOperatingLeaseRenewalOptions" name="NumberOfOperatingLeaseRenewalOptions" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_ExpectsToInvestmentInLeaseAmount" name="ExpectsToInvestmentInLeaseAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_MaximumPeriodOfAmountExpectedToInvestInLease" name="MaximumPeriodOfAmountExpectedToInvestInLease" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_FinanceLeaseAdditionalEquipmentSoldAmount" name="FinanceLeaseAdditionalEquipmentSoldAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_FinancingObligationsLeaseBackEquipmentAnnualRentAmount" name="FinancingObligationsLeaseBackEquipmentAnnualRentAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="beam_FinanceLeaseLiabilityPaymentsLineItems" name="FinanceLeaseLiabilityPaymentsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_FinanceLeaseLiabilityPaymentsTable" name="FinanceLeaseLiabilityPaymentsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_FinanceLeaseLiabilityPaymentsInterestPercentage" name="FinanceLeaseLiabilityPaymentsInterestPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="beam_SuccessPaymentPaidOrDue" name="SuccessPaymentPaidOrDue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_ProductDevelopmentAndRegulatoryApprovalMilestonesAndRoyaltiesRecognized" name="ProductDevelopmentAndRegulatoryApprovalMilestonesAndRoyaltiesRecognized" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_DevelopmentRegulatoryAndCommercialMilestonePayments" name="DevelopmentRegulatoryAndCommercialMilestonePayments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_EditasLicenseAgreementMember" name="EditasLicenseAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_PaymentOfUpfrontFee" name="PaymentOfUpfrontFee" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_PaymentOfMilestoneAmount" name="PaymentOfMilestoneAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="beam_BioPaletteLicenseAgreementMember" name="BioPaletteLicenseAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_BioPalettePatentMember" name="BioPalettePatentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_CollaborationArrangementExtendTerm" name="CollaborationArrangementExtendTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_StockIssuedDuringPeriodSharesNewIssuesFromRelatedParty" name="StockIssuedDuringPeriodSharesNewIssuesFromRelatedParty" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_PrimeMedicineIncMember" name="PrimeMedicineIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_TwoThousandNineteenEquityIncentivePlanMember" name="TwoThousandNineteenEquityIncentivePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_NumberOfFounderShareholders" name="NumberOfFounderShareholders" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="beam_FounderShareholdersMember" name="FounderShareholdersMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_ScientificConsultingAndOtherExpensesMember" name="ScientificConsultingAndOtherExpensesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="beam_VerveTherapeuticsIncMember" name="VerveTherapeuticsIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
</xsd:schema>
