The U.S. National Academies and the Russian Academy of Sciences convened a joint workshop to identify methods of overcoming impediments to cooperation between the United States and Russia on nonproliferation. The workshop emphasized approaches and techniques that have already been shown to work in U.S.-Russian programs and that might be applied in other areas. The workshop was intended to facilitate frank discussion between individuals in the United States and Russia who have some responsibility for cooperative nonproliferation programs in the hope of identifying both the impediments to cooperation and potential methods of addressing them. This report summarizes the discussions at the workshop.