When the Soviet Union collapsed in 1991, many observers feared that terrorists and rogue states would obtain weapons of mass destruction (WMD) or knowledge about how to build them from the vast Soviet nuclear, biological, and chemical weapons complex. The United States launched a major effort to prevent former Soviet WMD experts, suddenly without salaries, from peddling their secrets. In Our Own Worst Enemy, Sharon Weiner chronicles the design, implementation, and evolution of four U.S. programs that were central to this nonproliferation policy and assesses their successes and failures. Weiner examines the parlous state of the former Soviet nuclear, biological, and chemical weapons complex, the contentious domestic political debate within the United States, and most critically, the institutional interests and dynamics of the Defense, State, and Energy departments, which were charged with preventing the spread of WMD expertise. She explains why--despite unprecedented cooperation between the former Cold War adversaries--U.S. nonproliferation programs did not succeed at redirecting or converting to civilian uses significant parts of the former Soviet weapons complex. She shows how each of the U.S. government bureaucracies responsible for managing vital nonproliferation policies let its own organizational interests trump U.S. national security needs. Our Own Worst Enemy? raises important and troubling questions for anyone interested in understanding and improving policymaking and implementation processes in the area of nonproliferation and in U.S. national security policy more generally.