This book argues that community can exist at the international level, and that security politics is profoundly shaped by it, with states dwelling within an international community having the capacity to develop a pacific disposition. By investigating the relationship between international community and the possibility for peaceful change, this book revisits the concept first pioneered by Karl Deutsch: ‘security communities’. Leading scholars examine security communities in various historical and regional contexts: in places where they exist, where they are emerging, and where they are hardly detectable. Building on constructivist theory, the volume is an important contribution to international relations theory and security studies, attempting to understand the conjunction of transnational forces, state power and international organizations that can produce a security community.