The North Atlantic Treaty Organization (NATO) established the Partnership for Peace (PfP) to increase cooperation with former Warsaw Pact members and provide many of these countries with a path to NATO membership. As NATO confronts new security challenges, including the war in Afghanistan, its relationships with partner countries have grown in scope and importance. Additionally, NATO is developing a new Strategic Concept to clarify its mission and activities, including its relationship with PfP countries and other partners. The Department of Defense (DOD)-funded Warsaw Initiative Fund (WIF) supports the goals of the PfP program. GAO was asked to review (1) how the PfP program has evolved since GAO last reported on it in 2001; (2) options NATO is considering for the future of the PfP and other partnership programs; and (3) support to PfP countries through the U.S. WIF program. GAO analyzed NATO, DOD, and State Department (State) documents; and WIF funding data. GAO also interviewed DOD, State, NATO, and selected country officials.