This paper examines the status and prospects of the global, nuclear nonproliferation and disarmament regime. It finds that although the immediate crises over the North Korean and Iranian nuclear programs are serious, they are also likely manageable. Far more problematic for the regime’s long-term survival is the possible deterioration of the international security environment resulting from shifts in the global balance of power, severe climate change, and nuclear weapons retentionism by the current nuclear-armed states. Additionally, the accelerating spread of nuclear technology and expertise threatens to put nuclear weapons within easier reach of more states. Overall, the prospects for the regime remain uncertain and the window for action on nuclear nonproliferation and disarmament may be beginning to close. States should act now, and with resolve, to mitigate risks and to strengthen the regime in preparation for more challenging times ahead.