From a geopolitical perspective, the Asian littoral divides into three subregions: Northeast Asia (the People's Republic of China, Japan, North and South Korea, Taiwan and the Russian Far East), Southeast Asia (Brunei, Cambodia, East Timor, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam) and South Asia (India, Pakistan, Bangladesh, Nepal and Sri Lanka). Both Northeast Asia and South Asia contain political and economic Great Powers. In the latter, India's economic activities and growing politico-security influence extend to all of Asia. In the former, Japan, China, South Korea and Taiwan play significant global economic roles, while Tokyo and Beijing are also major political-security players. By contrast, Southeast Asia contains no Great Powers with global reach. While the region consists of several states with vibrant economies--Singapore, Malaysia, Thailand--or economic potential--Vietnam and Indonesia--in geopolitical stature, Southeast Asia pales in comparison to its Northeast and South Asia neighbours. Yet Southeast Asia is where most Asian regional organizations originate and whose structures and procedures are determined by Southeast Asian preferences. The primary goal of this article is to explain how this has happened, what the implications are for Asia's future and whether Southeast Asian states organized for the past forty years through the Association of Southeast Asian Nations (ASEAN) will be able to maintain their pivotal position in Asian affairs. For the past several decades, the Asia-Pacific region has been marked by a difficult asymmetry: the most dangerous disputes lie in Northeast and South Asia while the region's multilateral institutions designed to manage and reduce conflict have originated in Southeast Asia. While ASEAN has maintained its organizational integrity, it has added new internal and external dimensions. The former include the incipient ASEAN Free Trade Area (AFTA), the ASEAN Interparliamentary Organization which has been particularly vocal in condemning Myanmar's human rights violations, and the Track Three ASEAN People's Assembly, an NGO that brings a variety of societal interest groups together to lobby ASEAN governments. ASEAN-dominated organizations encompass the ASEAN Regional Forum (ARF) on security matters, ASEAN+3 (Japan, South Korea and China), various ASEAN+1 dialogues with important states, the ASEAN-Europe meeting (ASEM), and most recently, regular dialogues with the Gulf Cooperation Council, Africa and Latin America. The newest and most contentious addition to the mix is the East Asian Summit (EAS) inaugurated in December 2005. The EAS brings ASEAN+3 countries together with India, Australia and New Zealand--all of which have signed ASEAN's Treaty of Amity and Cooperation (TAC) as a membership condition. Conceptualizing ASEAN The Asia-Pacific region has no hegemon. Instead, political, economic and social networks proliferate. Regional issues are addressed through collective action. The various frameworks have diminished the strength of the absolute sovereignty norm that dominated ASEAN at the time of its 1967 creation. Over the ensuing decades, security issues have become increasingly transnational. Money laundering, human trafficking, environmental degradation, multi-national river development, migratory maritime species, terrorism and piracy require multilateral regime building rather than ad hoc diplomacy. In theory, at least, organizations such as ASEAN have established procedures and decision-making rules in which all governmental stakeholders have a voice. (2) Conceptualizing ASEAN, International Relations theorists generally employ three analytical frameworks: neo-realism, neoliberalism and constructivism. (3) Neo-realists disdain ASEAN's role in regional security because, in their view, institutions are epiphenomenal. Stability depends on the distribution of power within the Asia-Pacific and not on an international organization of small and medium states confined to Southeast Asia. …