-----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,
 EsHrYr/ZuNwlkqtBdh/g/MkhkJ1ITbvlge3eJnNfVwBe00iF1xw53d45g/b1IdvW
 1SSQggHVICyhE8KG7SLJcA==

<SEC-DOCUMENT>0001179110-09-011444.txt : 20090803
<SEC-HEADER>0001179110-09-011444.hdr.sgml : 20090801
<ACCEPTANCE-DATETIME>20090803124015
ACCESSION NUMBER:		0001179110-09-011444
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090803
FILED AS OF DATE:		20090803
DATE AS OF CHANGE:		20090803

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DRAPER E LINN JR
		CENTRAL INDEX KEY:			0001186296

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-10499
		FILM NUMBER:		09979495

	MAIL ADDRESS:	
		STREET 1:		AUSTIN STATE AFFAIRS OFFICE
		STREET 2:		400 W 15TH ST SUITE 1500
		CITY:			AUSTIN
		STATE:			TX
		ZIP:			78701-1677

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NORTHWESTERN CORP
		CENTRAL INDEX KEY:			0000073088
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRIC & OTHER SERVICES COMBINED [4931]
		IRS NUMBER:				460172280
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1206

	BUSINESS ADDRESS:	
		STREET 1:		125 S DAKOTA AVENUE
		STREET 2:		SUITE 1100
		CITY:			SIOUX
		STATE:			SD
		ZIP:			57104
		BUSINESS PHONE:		6059782908

	MAIL ADDRESS:	
		STREET 1:		125 S DAKOTA AVENUE
		STREET 2:		SUITE 1100
		CITY:			SIOUX
		STATE:			SD
		ZIP:			57104

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	NORTHWESTERN PUBLIC SERVICE CO
		DATE OF NAME CHANGE:	19920703
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-08-03</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000073088</issuerCik>
        <issuerName>NORTHWESTERN CORP</issuerName>
        <issuerTradingSymbol>NWE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001186296</rptOwnerCik>
            <rptOwnerName>DRAPER E LINN JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>3010 WEST 69TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SIOUX FALLS</rptOwnerCity>
            <rptOwnerState>SD</rptOwnerState>
            <rptOwnerZipCode>57108</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>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2009-08-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1033</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>24.20</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>46690</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">REPRESENTS SHARES UNDERLYING DEFERRED SHARE UNITS. THE SHARES UNDERLYING DEFERRED SHARE UNITS ARE ISSUABLE SUBSEQUENT TO THE REPORTING PERSON'S TERMINATION OF SERVICE AS A DIRECTOR.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>E. Linn Draper, Jr.</signatureName>
        <signatureDate>2009-08-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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