<SEC-DOCUMENT>0001488139-22-000046.txt : 20220308
<SEC-HEADER>0001488139-22-000046.hdr.sgml : 20220308
<ACCEPTANCE-DATETIME>20220308175002
ACCESSION NUMBER:		0001488139-22-000046
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20220304
FILED AS OF DATE:		20220308
DATE AS OF CHANGE:		20220308

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			STAVROPOULOS NICKOLAS
		CENTRAL INDEX KEY:			0001195025

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34811
		FILM NUMBER:		22723024

	MAIL ADDRESS:	
		STREET 1:		ONE MERROTECH CTR
		CITY:			BROOKLYN
		STATE:			NY
		ZIP:			11201

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Ameresco, Inc.
		CENTRAL INDEX KEY:			0001488139
		STANDARD INDUSTRIAL CLASSIFICATION:	CONSTRUCTION SPECIAL TRADE CONTRACTORS [1700]
		IRS NUMBER:				043512838
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		111 SPEEN STREET
		CITY:			FRAMINGHAM
		STATE:			MA
		ZIP:			01701
		BUSINESS PHONE:		508-661-2200

	MAIL ADDRESS:	
		STREET 1:		111 SPEEN STREET
		CITY:			FRAMINGHAM
		STATE:			MA
		ZIP:			01701
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_164677978472057.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2022-03-04</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001488139</issuerCik>
        <issuerName>Ameresco, Inc.</issuerName>
        <issuerTradingSymbol>AMRC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001195025</rptOwnerCik>
            <rptOwnerName>STAVROPOULOS NICKOLAS</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O AMERESCO, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>111 SPEEN STREET, SUITE 410</rptOwnerStreet2>
            <rptOwnerCity>FRAMINGHAM</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01701</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to puchase)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>13.37</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2022-03-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>30000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2022-03-04</value>
            </exerciseDate>
            <expirationDate>
                <value>2029-08-06</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>30000.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>30000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On August 6, 2019, the reporting person was granted an option to purchase 30.000 shares of Class A common stock. The option vested based on continued service to Ameresco, Inc. and performance relative to goals established for the three-year performance period from January 1, 2019 to December 31, 2021. Based on the level of achievement of these goals, as determined by Ameresco, Inc.'s Board of Directors, this option fully vested.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ David J. Corrsin, attorney-in-fact</signatureName>
        <signatureDate>2022-03-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
