Technical and economic considerations no longer prevent the acquisition of nuclear weapons by nations that do not have them. The technology is now widely known and generally accessible, and the cost is not prohibitive. For an increasing number of nations a decision to develop nuclear weapons rests on political and strategic factors. This book contains essays from a 1978 colloquium, jointly sponsored by the Central Intelligence Agency and the Department of Defense, that brought together 50 people from the academic, research organization, intelligence, and national security policymaking communities to discuss the essays and the questions generated by them.