Interregionalism, the institutionalized relations between world regions, is a new phenomenon in international relations. It also a new layer of development in an increasingly differentiated global order. This volume examines the structure of this phenomenon and the scholarly discourse it is generating. It takes stock of empirical facts and theoretical explanations, bringing together with clarity and concision the latest research on this key area. This essential new book: - traces the emergence of interregionalism and reviews the latest literature - provides a conceptual and theoretical framework for study - includes case studies of inter-regional relations between: Asia and America; Asia and Europe; Europe and America; and Europe and Africa. - delivers comparative analyses and special cases such as continental summits and interregional relationships beyond the Triad. - summarizes and evaluates the findings of each chapter, providing a basis for further research. This is a key reference book for students and researchers of regionalism, global governance and international relations.