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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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<SEC-DOCUMENT>0001179110-10-013709.txt : 20100913
<SEC-HEADER>0001179110-10-013709.hdr.sgml : 20100913
<ACCEPTANCE-DATETIME>20100913102424
ACCESSION NUMBER:		0001179110-10-013709
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100910
FILED AS OF DATE:		20100913
DATE AS OF CHANGE:		20100913

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Marucci Anthony S
		CENTRAL INDEX KEY:			0001429933

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-15006
		FILM NUMBER:		101068374

	MAIL ADDRESS:	
		STREET 1:		66 COLD HILL DRIVE
		CITY:			MENDAHM
		STATE:			NJ
		ZIP:			07945

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Celldex Therapeutics, Inc.
		CENTRAL INDEX KEY:			0000744218
		STANDARD INDUSTRIAL CLASSIFICATION:	IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES [2835]
		IRS NUMBER:				133191702
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		119 FOURTH AVE
		CITY:			NEEDHAM
		STATE:			MA
		ZIP:			02494
		BUSINESS PHONE:		7814330771

	MAIL ADDRESS:	
		STREET 1:		119 FOURTH AVE
		CITY:			NEEDHAM
		STATE:			MA
		ZIP:			02494-2725

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	AVANT IMMUNOTHERAPEUTICS INC
		DATE OF NAME CHANGE:	19980828

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	T CELL SCIENCES INC
		DATE OF NAME CHANGE:	19920703
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-09-10</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000744218</issuerCik>
        <issuerName>Celldex Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>CLDX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001429933</rptOwnerCik>
            <rptOwnerName>Marucci Anthony S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CELLDEX THERAPEUTICS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>119 FOURTH AVENUE</rptOwnerStreet2>
            <rptOwnerCity>NEEDHAM</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02494</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President &amp; CEO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

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                <transactionCode>P</transactionCode>
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                <transactionShares>
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                <transactionPricePerShare>
                    <value>3.46</value>
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                <transactionAcquiredDisposedCode>
                    <value>A</value>
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            <transactionDate>
                <value>2010-09-10</value>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>200</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.4598</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
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                <sharesOwnedFollowingTransaction>
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        <nonDerivativeTransaction>
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                <value>Common Stock</value>
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            <transactionDate>
                <value>2010-09-10</value>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>200</value>
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                <transactionPricePerShare>
                    <value>3.47</value>
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                <transactionAcquiredDisposedCode>
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            <postTransactionAmounts>
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            <transactionAmounts>
                <transactionShares>
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                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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                <sharesOwnedFollowingTransaction>
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            <transactionDate>
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            <transactionAmounts>
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                    <value>1400</value>
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                    <value>319</value>
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                <transactionPricePerShare>
                    <value>3.4589</value>
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            <ownershipNature>
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    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <ownerSignature>
        <signatureName>Anthony S. Marucci</signatureName>
        <signatureDate>2010-09-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----