In this paper, Lt. Col. Devin L. Cate tackles the question of whether an air superiority fighter is relevant to warfare in the twenty-first century. Critics of the F/A-22, the US Air Force's next generation air superiority fighter, have identified it as a cold war relic - unjustifiably expensive and out of step with the Department of Defense (DoD) transformation. Colonel ate argues that the six operational goals of the DoD transformation, as defined in the Quadrennial Defense Review Report (QDR) of 2001, actually demand a highly capable air superiority fighter. He shows how achieving these transformational operational goals requires performance of the four offensive counterair functions of surface attack, fighter sweep, escort, and suppression of enemy air defenses (SEAD), as well as defensive counterair. He demonstrates that only an air superiority fighter can efficiently and effectively satisfy all these functions. Colonel Cate then identifies the operational requirements for an air superiority fighter to adequately contribute to the operational goals of the transformation. These requirements are superlative air-to-air and air-to-ground performance, survivability against modern air defense systems, and a capable sensor suite that allows the fighter to be a sensor-shooter and participate in the joint data network. Finally, Colonel Cate assesses the leading candidates for a twenty-first century fighter - the F-15C/E, F/A-22, F-35A, uninhabited combat aerial vehicle (UCAV), and the common aerospace vehicle (CAV) - against these requirements. The proliferation of advanced air defense capabilities during the next few years will seriously challenge the suitability of the aging F-15C/E as an air superiority fighter. He notes that while the UCAV holds long-term promise an air superiority platform, we still have much to do in developing its capability and the doctrine, tactics, and training to employ the UCAV in the air-to-air mission, especially against manned air-to-air threats in close engagements. Consequently, Colonel Cate concludes the F/A-22 is the only fighter that will meet all the requirements for a transformational air superiority fighter by 2007. This paper provides rich material for discussion not only about the role of the air superiority fighter in the twenty first century but also concerning the nature of defense transformation itself.