Diversification's legitimation challenges: ASEAN and its Myanmar predicament.

The article examines how internal diversification within international organizations (IOs) complicates their legitimation strategies, focusing on the Association of Southeast Asian Nations (ASEAN) and its longstanding challenges related to Myanmar's membership. Drawing on Lenz and Söderbaum's agents-audience-environment (AAE) framework, it identifies three key sources of internal diversification—domestic change, new membership, and expanded institutional purposes—that affect both the agents and audiences of legitimation. Through analysis of ASEAN's responses to Myanmar's crises across three periods marked by varying degrees of diversification, the article highlights ASEAN's evolving legitimation strategies, including strategic reconciliation, selective accommodations, and defensive workarounds such as ambiguation and depoliticization. It concludes that internal diversification intensifies tensions between competing legitimacy demands from diverse internal and external audiences, making ASEAN's legitimation efforts dynamic, contested, and constrained by foundational norms like non-interference and regional unity.