Environmental challenges are often transnational and affect the daily lives of people as well as broader national interests. This research paper focuses on the challenge of finding a balance between economic development and environmental degradation in the Mekong subregion and assesses the role of regional institutions in dealing with this issue. Finding a balance is important, because more than 70 million people live on the river banks and the subregion is crucial for the economic development of its six riparian countries. Concentrating on two organizations - the Mekong River Commission (MRC) and the Greater Mekong Subregion (GMS) - this article argues that regional attempts to find a balance have so far largely failed. Reasons for this lack of success include the MRC's failure to include all riparian countries, and the fact that the GMS has only recently widened its focus from economic development to also include environmental and social issues.