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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 PGKzXCgz12kBtFPnFuW9chQSCtfyEWbehu93AAsVxVqFqJa+FkejI3m4ImL3yso4
 eB+YbwU81rHFCTPUmBk1NQ==

<SEC-DOCUMENT>0000851520-08-000106.txt : 20080602
<SEC-HEADER>0000851520-08-000106.hdr.sgml : 20080602
<ACCEPTANCE-DATETIME>20080602195523
ACCESSION NUMBER:		0000851520-08-000106
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080529
FILED AS OF DATE:		20080602
DATE AS OF CHANGE:		20080602

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			EXPONENT INC
		CENTRAL INDEX KEY:			0000851520
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-MANAGEMENT CONSULTING SERVICES [8742]
		IRS NUMBER:				770218904
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1230

	BUSINESS ADDRESS:	
		STREET 1:		EXPONENT INC
		STREET 2:		149 COMMONWEALTH DRIVE
		CITY:			MENLO PARK
		STATE:			CA
		ZIP:			94025
		BUSINESS PHONE:		650-326-9400

	MAIL ADDRESS:	
		STREET 1:		EXPONENT INC
		STREET 2:		149 COMMONWEALTH DRIVE
		CITY:			MENLO PARK
		STATE:			CA
		ZIP:			94025

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	FAILURE GROUP INC
		DATE OF NAME CHANGE:	19930831

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ARMACOST SAMUEL H
		CENTRAL INDEX KEY:			0001194899

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-18655
		FILM NUMBER:		08875386

	BUSINESS ADDRESS:	
		STREET 1:		SRI INTERNATIONAL
		STREET 2:		333 RAVENSWOOD AVENUE
		CITY:			MENLO PARK
		STATE:			CA
		ZIP:			94025
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgardoc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-05-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000851520</issuerCik>
        <issuerName>EXPONENT INC</issuerName>
        <issuerTradingSymbol>EXPO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001194899</rptOwnerCik>
            <rptOwnerName>ARMACOST SAMUEL H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>149 COMMONWEATH DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-05-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1201</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1201</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1201</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">1-for-1.</footnote>
        <footnote id="F2">Restricted stock units will vest in three (3) equal installments on the day prior to the Company's annual shareholder meeting.  Shares of Common Stock will be issued to the reporting person on the third vesting date.</footnote>
        <footnote id="F3">Not applicable.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>By: Wendy Whitehouse  For: Samuel H. Armacost</signatureName>
        <signatureDate>2008-06-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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