This report assesses the achievements of the Mekong River Commission, an organisation where Thailand, Lao PDR, Cambodia and Vietnam cooperate about the Mekong River which runs through all four. Burma and China, the furthest upstream, do not participate, but hold observer status. The study uses a model outlined by Arild Underdal (in Miles et al, 2002) to understand and account for the effectiveness or lack thereof of the regime. The main explanatory factors are the problem malignity of the cooperation of the river, the low problem-solving capacity of the regime and its members, and other arrangements for cooperation in the region. The report argues that geographical location along the river, combined with size of territory within the river basin, determines the potential for pusher and laggard roles within the regime, while domestic conditions in the state affect whether this potential is fulfilled or not.