This is the first book that examines in detail how NATO, an institution with deep roots in the Cold War, has adapted to one of the new threats currently dominating global civil society - that of Weapons of Mass Destruction. It looks critically at where NATO has been effective in addressing WMD proliferation threats, and where it has not made a major contribution. It explains the reasons why, illustrating the difficulties that established multilateral institutions, not just NATO, have in addressing new challenges. Finally, the book points the way ahead. Of existing multilateral institutions, only NATO has intervened militarily with success in high-risk situations. It has unique experience in the military aspects of post-conflict stabilization under conditions of considerable residual risk. Improving the alliance's ability to perform these roles in the face of WMD threats is a top objective. Building habits of cooperation within and among partner countries is something else NATO does well, and is part of a broad-ranging international effort to deal more effectively with new risks. Defining NATO's role in the international institutional architecture for dealing with proliferation-related threats remains a challenge. The alliance also should be one important forum for addressing questions about the construction of new post-Cold War security rules, but much will depend on the policies of NATO's largest member, the USA, currently sceptical of traditional multilateralism. The book will be of interest to students of NATO, defence policy, weapons proliferation and Security Studies in general.