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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 xUjsHHrLomVFl1k67d2azA==

<SEC-DOCUMENT>0000891106-06-000016.txt : 20060213
<SEC-HEADER>0000891106-06-000016.hdr.sgml : 20060213
<ACCEPTANCE-DATETIME>20060213182950
ACCESSION NUMBER:		0000891106-06-000016
CONFORMED SUBMISSION TYPE:	5
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20051231
FILED AS OF DATE:		20060213
DATE AS OF CHANGE:		20060213

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SPIRES DIANNE E
		CENTRAL INDEX KEY:			0001199239

	FILING VALUES:
		FORM TYPE:		5
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-20800
		FILM NUMBER:		06605725

	MAIL ADDRESS:	
		STREET 1:		224 MTN VIEW BLVD
		CITY:			KLAMATH FALLS
		STATE:			OR
		ZIP:			97601

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>5
<SEQUENCE>1
<FILENAME>doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>5</documentType>

    <periodOfReport>2005-12-31</periodOfReport>

    <form3HoldingsReported>0</form3HoldingsReported>

    <form4TransactionsReported>0</form4TransactionsReported>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001199239</rptOwnerCik>
            <rptOwnerName>SPIRES DIANNE E</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>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-02-13</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2005-12-31</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1655</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>24.98</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7831</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Adjustment reflects shares erroneously added for exercises that occurred during 2005.  Balance is correct in reference to Mrs. Spires' common stock records.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>E. Marie Hirsch</signatureName>
        <signatureDate>2006-02-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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