<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-11-18</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001762359</issuerCik>
        <issuerName>Acreage Holdings, Inc.</issuerName>
        <issuerTradingSymbol>ACRG.A</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001796979</rptOwnerCik>
            <rptOwnerName>Doherty James A III</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>366 MADISON AVENUE, 11TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>General Counsel</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock - Class D Subordinate Voting Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2020-11-18</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>659</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.1504</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>382519</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock - Class E Subordinate Voting Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2020-11-18</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
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            <transactionAmounts>
                <transactionShares>
                    <value>1489</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.4415</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>892594</value>
                    <footnoteId id="F2"/>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </nonDerivativeTransaction>
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    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>7.5</value>
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            <exerciseDate>
                <footnoteId id="F3"/>
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            <expirationDate>
                <value>2028-11-14</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock - Class D Subordinate Voting Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>72000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>72000</value>
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                <directOrIndirectOwnership>
                    <value>D</value>
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            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
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            <exerciseDate>
                <footnoteId id="F3"/>
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            <expirationDate>
                <value>2028-11-14</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock - Class E Subordinate Voting Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>168000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>168000</value>
                    <footnoteId id="F2"/>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Common Units of High Street Capital Partners, LLC</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F4"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F4"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>See Footnote</value>
                    <footnoteId id="F4"/>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>210373</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>210373</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Shares sold solely for the purpose of paying taxes applicable as a result of the vesting of restricted stock units.</footnote>
        <footnote id="F2">Pursuant to the Amended Arrangement between Canopy Growth Corporation and Acreage Holdings, Inc., implemented on September 23, 2020, Acreage's articles have been amended to create new Class E subordinate voting shares (the &quot;Fixed Shares&quot;), Class D subordinate voting shares (the &quot;Floating Shares&quot;) and Class F multiple voting shares (the &quot;Fixed Multiple Shares&quot;). Each existing Class A subordinate voting share of Acreage (each, a &quot;Subordinate Voting Share&quot;) has been exchanged for 0.7 of a Fixed Share and 0.3 of a Floating Share, each existing Class B proportionate voting share (each, a &quot;Proportionate Voting Share&quot;) has been exchanged for 28 Fixed Shares and 12 Floating Shares and each existing Class C multiple share (each, a &quot;Multiple Voting Share&quot;) has been exchanged for 0.7 of a Fixed Multiple Share and 0.3 of a Floating Share.</footnote>
        <footnote id="F3">One-third of the options vested on November 14, 2019. The remaining options vest ratably over the subsequent eight quarters.</footnote>
        <footnote id="F4">These Units are convertible into 0.7 of a Class E subordinate voting share and 0.3 of a Class D subordinate voting share or the cash equivalent thereof at the option of Acreage Holdings, Inc. as set forth in the High Street Capital Partners, LLC Third Amended and Restated Operating Agreement.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Jessica S. Lochmann, Attorney-in-Fact for James A. Doherty III</signatureName>
        <signatureDate>2020-11-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
