ASEAN has been recognized as a successful regional institution. Initially, ASEAN aimed to strengthen regional cooperation rather than regional integration. The movement towards regional integration gained strength since the end of the Cold War and particularly since the economic crisis of 1997-1998. Leaders of ASEAN member countries agreed to create an ASEAN Economic Community (AEC) in 2002. This ambitious plan, however, face challenges due to the diversity of economic development and structure, and the lack of political will. This book reveals the degree of regional integration, particularly in economic field, and investigates its limitations and challenges.