NATO has made important contributions to regional security in post-Cold War Southeastern Europe. Engagement with the alliance's security assistance programs provides opportunities for security sector reform and professional development, helps to reorient national defense and security policies toward contemporary challenges, and places the responsibility of territorial defense in a collective security framework that allows for a more efficient utilization of limited resources and reduces the likelihood of interstate conflict. All the countries of the Western Balkans are committed to cooperation with the alliance, and to varying degrees are moving toward (or have already achieved) closer or full association, a process that this article seeks to document. NATO membership is also often perceived, rightly or wrongly, as a necessary step along the road toward membership in the European Union, the most important strategic goal for the majority of Western Balkan states. Association with the alliance is not, however, a sufficient foundation for regional stability and cooperative security. This will require a more complex process of development, including economic, political, social and cultural dimensions. Inclusive policies, including more effective cooperation between NATO and the Russian Federation in pursuit of mutual interests, would be of particular value.