This book focuses on the problem of regionalism, the crucial phenomenon in international relations at the turn of the 20th and 21st centuries. Regionalism is analyzed both in terms of regional economic and political integration, as well as regional competition and conflict. The book is divided into three parts, based on the functional and geographical criteria. The first part is devoted to the theoretical setting, including brief introduction to regionalism problems and classical theories of integration, as well as new approaches to regionalism, which are followed by the analysis of regions in the context of regional security complexes concept. The second part of the book focuses on Asian and African challenges to regionalism and the third, and final, part is devoted to the most developed subregional order, namely the European region.