-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 K3bxSx4YEmvP43lw1HjXTIq0b1BL9egbMPoQe/IRriwUJOORUKne0GPs241hbE2N
 gJyabZY3n92R+xQEFAzGog==

<SEC-DOCUMENT>0001123292-11-000165.txt : 20110223
<SEC-HEADER>0001123292-11-000165.hdr.sgml : 20110223
<ACCEPTANCE-DATETIME>20110223193210
ACCESSION NUMBER:		0001123292-11-000165
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20110218
FILED AS OF DATE:		20110223
DATE AS OF CHANGE:		20110223

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			HUSTON EDWIN A
		CENTRAL INDEX KEY:			0001185124

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	333-48123
		FILM NUMBER:		11633707

	MAIL ADDRESS:	
		STREET 1:		UNISYS CORP
		STREET 2:		UNISYS WAY
		CITY:			BLUE BELL
		STATE:			PA
		ZIP:			19424-0001

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			HACKETT GROUP, INC.
		CENTRAL INDEX KEY:			0001057379
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-MANAGEMENT CONSULTING SERVICES [8742]
		IRS NUMBER:				650750100
		STATE OF INCORPORATION:			FL
		FISCAL YEAR END:			1228

	BUSINESS ADDRESS:	
		STREET 1:		1001 BRICKELL BAY DRIVE
		STREET 2:		SUITE 3000
		CITY:			MIAMI
		STATE:			FL
		ZIP:			33131
		BUSINESS PHONE:		3053758005

	MAIL ADDRESS:	
		STREET 1:		1001 BRICKELL BAY DRIVE
		STREET 2:		SUITE 3000
		CITY:			MIAMI
		STATE:			FL
		ZIP:			33131

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ANSWERTHINK INC
		DATE OF NAME CHANGE:	20000628

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ANSWERTHINK CONSULTING GROUP INC
		DATE OF NAME CHANGE:	19980608
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-02-18</periodOfReport>

    <issuer>
        <issuerCik>0001057379</issuerCik>
        <issuerName>HACKETT GROUP, INC.</issuerName>
        <issuerTradingSymbol>HCKT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001185124</rptOwnerCik>
            <rptOwnerName>HUSTON EDWIN A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O THE HACKETT GROUP, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1001 BRICKELL BAY DRIVE, SUITE 3000</rptOwnerStreet2>
            <rptOwnerCity>MIAMI</rptOwnerCity>
            <rptOwnerState>FL</rptOwnerState>
            <rptOwnerZipCode>33131</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-02-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>16667</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>37132</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-02-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>16667</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>53799</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents a grant of restricted stock units (RSUs).  The RSUs vest in three equal annual installments beginning February 18, 2012.  Upon vesting of the RSUs, the reporting person receives shares of common stock on a one-for-one basis.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Frank A. Zomerfeld, Attorney-in-Fact</signatureName>
        <signatureDate>2011-02-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----