As the center of gravity in international relations pivots to Asia-Pacific, the ASEAN region is emerging as both an important player on the global stage and an arena of international competition that includes a power struggle between the U.S. and China. With ASEAN's competitiveness on the rise, however, its unity is hardly certain. In a changing world, economic and political protectionism gains a foothold. The book synthesizes our knowledge about ASEAN, with a specific emphasis on hot-button issues ranging from its domestic dynamics to external relations. It also reflects an evolution in ASEAN studies, which have largely shifted from a purely economic approach to understanding the region to a security-oriented one. Collectively, this book conveys an unambiguous and urgent message: ASEAN matters.