While European integration advances, many of the countries along Europe's eastern and southern periphery have fallen prey to chronic conflict punctuated by a series of small wars. Exacerbating the situation has been the lack of effective organizational means for mediating local conflicts, facilitating regional development and structuring cooperation with larger regional and international institutions. What are the prospects for enhancing security in the most volatile subregions of post-communist Europe? This text examines the external and internal factors that impede or foster subregional cooperation in South-Eastern and East-Central Europe and the Caucasus. It includes chapters situating these borderlands in the context of a wider Europe with an evolving security architecture.