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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 TgDnYxykIx/kMKYOOG2v/KD2D0p0/AIk686sAM1HETw6+merGaRA1UXEnvaTegdd
 JtE33DzNaGih7v7cfdk8Pg==

<SEC-DOCUMENT>0000891106-05-000067.txt : 20051221
<SEC-HEADER>0000891106-05-000067.hdr.sgml : 20051221
<ACCEPTANCE-DATETIME>20051221163844
ACCESSION NUMBER:		0000891106-05-000067
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20051219
FILED AS OF DATE:		20051221
DATE AS OF CHANGE:		20051221

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BOONE THOMAS HUTTON
		CENTRAL INDEX KEY:			0001256132

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-20800
		FILM NUMBER:		051278992

	MAIL ADDRESS:	
		STREET 1:		111 NORTH WALL STREET
		CITY:			SPOKANE
		STATE:			WA
		ZIP:			99201-0696

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			STERLING FINANCIAL CORP /WA/
		CENTRAL INDEX KEY:			0000891106
		STANDARD INDUSTRIAL CLASSIFICATION:	SAVINGS INSTITUTIONS, NOT FEDERALLY CHARTERED [6036]
		IRS NUMBER:				911572822
		STATE OF INCORPORATION:			WA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		111 N WALL ST
		CITY:			SPOKANE
		STATE:			WA
		ZIP:			99201
		BUSINESS PHONE:		509-354-8165

	MAIL ADDRESS:	
		STREET 1:		111 NORTH WALL STREET
		CITY:			SPOKANE
		STATE:			WA
		ZIP:			99201
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-12-19</periodOfReport>

    <issuer>
        <issuerCik>0000891106</issuerCik>
        <issuerName>STERLING FINANCIAL CORP /WA/</issuerName>
        <issuerTradingSymbol>STSA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001256132</rptOwnerCik>
            <rptOwnerName>BOONE THOMAS HUTTON</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>111 N. WALL STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SPOKANE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>99201</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>Non-Statutory Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>25.71</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-12-19</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2005-12-19</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>25.71</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2005-12-19</value>
            </exerciseDate>
            <expirationDate>
                <value>2015-12-18</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes></footnotes>

    <ownerSignature>
        <signatureName>E. Marie Hirsch</signatureName>
        <signatureDate>2005-12-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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