For nearly two decades, ASEAN has served as a vehicle for the postsocialist states of Cambodia, Laos, Myanmar, and Vietnam (CLMV) to seek diplomatic recognition and enmesh their economies with the dominant discourses, structures, and visions of post-Cold War capitalist modernity. In scholarly and lay understandings of how CLMV states "integrate" through ASEAN, attention has been firmly on the political, security, and economic outcomes of ASEAN-CLMV interactions, with diplomacy viewed as a passive instrument to pursue such outcomes. Such a static view of diplomacy, I argue, obscures a vital mechanism in and through which these broader macro-social changes are being sought and accomplished. As they pursue modernist state projects, diplomats too must yield to experiences of learning and redefinition to express (and enable) the project of international "integration". This paper examines such processes of learning and redefinition by studying the effects and consequences of immersion in English-based ASEAN multilateral work for the diplomats of CLMV states. It delves into the Attachment Officers Programme for CLMV diplomats at the ASEAN Secretariat in Jakarta as an illustrative case to tease out the skills CLMV diplomats gain from their stints in ASEAN work. These skills — the ability to draft quasi-diplomatic documents in English, facility with speaking English, and an embodied ease in interacting with foreigners (both Asian and Euro-American) — are generic but also transposable as these junior diplomats embark on representational and negotiating roles for their countries. The paper demonstrates how stints in ASEAN multilateral diplomacy have emerged as a channel for exposure and grooming for CLMV diplomats as they themselves "integrate" with an English-based global (yet Eurocentric) diplomacy.