This paper considers ASEAN’s value added and limitations as regards its ability to play a meaningful and practical security role in East Asia and the Asia Pacific. It argues that ASEAN’s contributions to regional security and within ASEAN-plus arrangements are not uniform. Instead, they vary depending on the relationship and the arrangement. This paper gives particular attention to two sets of relations: 1) ASEAN’s relations with major powers; and 2) major power relations with one another. It argues that the latter has proven most challenging in terms of both practical changes to the regional security environment and growing questions about the appropriateness and capacity of ASEAN to “lead” institutional arrangements, but that such challenges may also vary depending on which major power relationship or regional institution is in question. It further argues that ASEAN’s challenges are also conditioned by security contributions that are often understated, though dissatisfactions from both inside and outside the organization are likely to remain persistent challenges to ASEAN ability to defend its current role.