The paper analyses the security dimension of the Greater Mekong Subregion (GMS) by taking into account traditional as well as non-traditional security issues. The Greater Mekong Subregion, which was established in 1992 at the initiative of the ADB, emerged after the Cold War in the wake of the so-called new regionalism as one of the growth triangles within ASEAN. Participating countries/regions are China's Yunnan province, Myanmar, Thailand, Vietnam, Cambodia and Laos. The article places the discussion of the Greater Mekong Subregion within the debate on post-Cold War sub-regionalism and sets out to discuss the development of regionalism in the Mekong Basin. The article shows how economic cooperation is followed in the pursuit of security and stability in a formerly conflict-ridden area and assesses the relevance of the GMS towards the issue of conflict reduction in the Mekong Basin.