This thesis studies Thailand-Vietnam relations in the 1990s. Since Vietnam invaded Cambodia at the end of 1978, their bilateral relations became poor. In 1986, Vietnam implemented the “Doi Moi” policy to solve domestic economic problems. Chatichai Choonhavan the leader of Thailand responded to this new policy of Vietnam with the “turning the Indochina battlefields into market places” policy. These new policies improved the relations between the two countries. In the early 1990s, Thailand and Vietnam focused their cooperation on economic issues. They could agree on many sensitive issues in the late 1990s and cooperated in various areas. In the post-Cold War period, the major powers were unreliable for Vietnam. Unlike the regional organizations established earlier, ASEAN tried to avoid being influenced by major powers. Vietnam became more involved in ASEAN and gained membership in 1995 with Thailand’s support. Thailand and Vietnam also cooperated in sub-regional organizations.