-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 EKleVcHrlb8+bKbl/Ii6LGQ1VhUYuCll3vez3rYDdVXzvQb5NZCvEmEh30/NCdug
 b1PPUETjG0CiaxxGK4a1Qw==

<SEC-DOCUMENT>0000851520-08-000138.txt : 20081112
<SEC-HEADER>0000851520-08-000138.hdr.sgml : 20081111
<ACCEPTANCE-DATETIME>20081112160235
ACCESSION NUMBER:		0000851520-08-000138
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20081103
FILED AS OF DATE:		20081112
DATE AS OF CHANGE:		20081112

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:			Lange Robert C
		CENTRAL INDEX KEY:			0001449831

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-18655
		FILM NUMBER:		081180876

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		650-326-9400

	MAIL ADDRESS:	
		STREET 1:		149 COMMONWEALTH DRIVE
		CITY:			MENLO PARK
		STATE:			CA
		ZIP:			94025
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>edgardoc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2008-11-03</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001449831</rptOwnerCik>
            <rptOwnerName>Lange Robert C</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>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Group Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <ownerSignature>
        <signatureName>By: Bill Homan  For: Robert C. Lange</signatureName>
        <signatureDate>2008-11-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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