This book examines an important economic development in East Asia during the first decade of the 21st century. Whereas regional arrangements were, with the sole significant exception of ASEAN, conspicuously absent before 2000, they have proliferated since 2000 in both the monetary and trade areas. The book places this political development in the changing nature of the national economies, especially their increasing integration into regional and global value chains with the fragmentation of production processes. This is a freshly written, coherent analysis of the topic, drawing upon (updated) material from a series of articles that the author has published on the subject over the years. Although the book is based on theoretical and, especially, empirical analysis of regionalism, it is written in a non-technical style accessible to a wide range of readers. The book is likely to be adopted as supplementary reading for university courses on Asian economies, whether be it in area studies or economics/political economy disciplines.