UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): February 8, 2011

This combined Form 8-K is separately filed by Alliant Energy Corporation, Interstate Power and Light Company and Wisconsin Power and Light Company.

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

(b) (c) On February 9, 2011, the Board of Directors (the “Board”) of Alliant Energy Corporation (“Alliant Energy”), Interstate Power and Light Company (“IP&L”) and Wisconsin Power and Light Company (“WP&L,” and together with Alliant Energy and IP&L, the “Company”) made several executive officer appointments as part of its succession planning efforts.

The Board appointed Patricia L. Kampling, 51, as Alliant Energy’s President and Chief Operating Officer, and the Chief Operating Officer of IP&L and WP&L, all effective February 9, 2011. Ms. Kampling has served as Executive Vice President and Chief Financial Officer of the Company since 2010, Vice President-Chief Financial Officer and Treasurer from 2008 to 2010, Vice President and Treasurer from 2007 to 2008 and Vice President-Finance from 2005 to 2007. William D. Harvey will no longer be president of Alliant Energy, but will remain chairman and chief executive officer of the Company. Ms. Kampling will no longer be chief financial officer of the Company.

The Board appointed Thomas L. Hanson, 57, as the Company’s Vice President - Chief Financial Officer and Treasurer effective February 9, 2011. Mr. Hanson has served as the Company’s Vice President-Chief Accounting Officer and Treasurer since 2010, Vice President-Controller and Chief Accounting Officer from 2007 to 2010 and Vice President and Treasurer from 2002 to 2007. Mr. Hanson will no longer be chief accounting officer of the Company.

The Board appointed Robert J. Durian, 40, as the Company’s Controller and Chief Accounting Officer effective February 9, 2011. Mr. Durian has served as Controller of the Company since 2010, Assistant Controller of the Company from 2009 to 2010 and Director or Manager of Financial Reporting of the Company from 2003 to 2009.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, Alliant Energy Corporation, Interstate Power and Light Company and Wisconsin Power and Light Company have each duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

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