Thomas Biersteker, Brown University; Paula DeSutter, U.S. Department of State; Shen Dingli, Fudan University; Skip Fischer, U.S. Senate Committee on Banking, Housing, and Urban Affairs. This session was part of the 2007 Carnegie International Nonproliferation Conference, “Tomorrow's Solutions,” June 25–26, in Washington, D.C., which addressed the critical challenges confronting the nonproliferation regime and offered policy recommendations to stop the spread and use of nuclear weapons and materials.