Is the Association of Southeast Asian Nations (ASEAN) a pluralistic security community (PSC)? Does community cause security in Southeast Asia? In a PSC, member states are sovereign. So are the members of ASEAN. Before concluding that the ASEAN region is a PSC, however, one should distinguish between two versions: a thin or descriptive PSC, whose members share both a sense of community and the expectation of security, and a thick or explanatory version in which community has actually been shown to cause security. Depending on how a sense of community is defined, one may say that at certain times in its history, ASEAN probably has been a thin PSC. More recently, however, the cooperative identity of regional elites may have frayed, as democratization, especially in Indonesia, has incorporated non-elites into public life. Meanwhile the proposition that the assurance of security in Southeast Asia has resulted from this sense of community, that ASEAN is a thick PSC, remains to be proven.