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:

     This combined Form 8-K is separately filed by Pinnacle West Capital Corporation and Arizona Public Service Company. Each registrant is filing on its own behalf all of the information contained in this Form 8-K that relates to such registrant and, where required, its subsidiaries. Except as stated in the preceding sentence, neither registrant is filing any information that does not relate to such registrant, and therefore makes no representation as to any such information.

     On April 18, 2007, the Board of Directors of Pinnacle West Capital Corporation (the “Company”) adopted an amendment (the “Amendment”) to the Pinnacle West Capital Corporation 2007 Long-Term Incentive Plan (the “2007 Plan”). The Amendment provides that the term of any Stock Appreciation Rights (as defined in the 2007 Plan) granted under the 2007 Plan will not exceed ten years. The 2007 Plan is subject to the approval of the Company’s shareholders at the Company’s 2007 Annual Meeting of Shareholders to be held on May 23, 2007.

     If the shareholders approve the 2007 Plan, the Company will not issue any additional shares or awards under the Pinnacle West Capital Corporation 2002 Long-Term Incentive Plan (the “2002 Plan”) or under the Directors Equity Plan. At March 31, 2007, a total of 1,475,771 shares of Company common stock could potentially be issued pursuant to outstanding awards under the 2002 Plan, a substantial portion of which are subject to the achievement of three-year performance measures. No awards have been made under the 2002 Plan since March 31, 2007 and no awards will be made under the 2002 Plan before the 2007 Annual Meeting of Shareholders. Exhibit 99.1 provides information regarding outstanding stock awards at December 31, 2006 and March 31, 2007.

     Pursuant to the requirements of the Securities Exchange Act of 1934, each registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.