The abrupt end of the Cold War has created a security environment where many nations are now reconsidering acquiring independent nuclear weapons capability. Ahead is a planetary condition where virtually any industrialized nation will have the scientific infrastructure necessary to produce nuclear weapons and associated delivery vehicles indigenously, and at an economically affordable cost. Many nations may choose to maintain "virtual nuclear arsenals" that by plan can be reliably assembled inside a nation's notional strategic warning time for the appearance of dire political-military threats. This report confronts the challenge of containing these tendencies in the direction of a more favorable end state. The authors set forward four illustrative alternative end states: (1) "High Entropy" Deterrence--a highly proliferated world with few "rules of the nuclear road"; (2) An Ever-Slowly-Expanding Nuclear Club--an inexorable slow growth in the number of nuclear-armed states; (3) a Two-Tiered Static "Have-a-Lot/Have-None" System--a handful of "haves" maintain substantial "at-the-ready" nuclear arsenals and commit to maintaining the security of the "have-nots"; and (4) the Virtual Abolition of Nuclear Arsenals--a handful of states maintain a few hundreds of nuclear weapons with a highly intrusive inspection and collective enforcement regime. The 1995 NPT Review and Extension Conference looms large as a key passage which will reveal the direction that the world's leading nations will take on the nuclear proliferation problem.