The middle powers literature often conflates role identity (national self-conception) of middle power states with role performance (foreign policies), while neglecting East Asia as a region of hypothesis generation and testing. Empirical studies of middle powers tend to consider European cases, Canada, Australia and South Africa, while research on contemporary East Asia international relations focuses on great powers or the development of regional institutions. This article contributes to the middle powers literature by comparing the post-Cold-War national identities and foreign policies of South Korea and Vietnam. A framework for analyzing national identity is applied to major sources of national self-conceptions in Seoul and Hanoi. The article examines how identity trajectories relate to change in South Korea and Vietnam's geopolitical positioning between the United States and China, and assesses the prospects for middle power cooperation in East Asia.