Indonesia has traditionally been viewed as a de facto leader of the Association of Southeast Asian Nations (ASEAN) and the regional body remains the cornerstone of Indonesian foreign policy. The paper addresses the question of whether other member states have become influential actors or even sectoral leaders in their own right by playing a direct role in a particular aspect of ASEAN affairs. This question is addressed by examining the regional policies of Vietnam, a country that has been mostly neglected in the existing ASEAN literature despite its strategic weight. The paper focuses on the evolving role of Vietnam in ASEAN and highlights its diplomatic initiatives, as well as various conditions to evaluate its potential to take up a leading security role in the regional body in the years to come.