Responses to climate change in a transboundary river basin depend not on national and subnational capacities alone, but also on the ability of co-riparian nations to communicate, coordinate and cooperate across their international boundary. Evaluating transboundary river basins in light of their transboundary adaptive capacity sheds lights on likely ‘hotspots’ or areas of concern, as a lack of adaptive capacity in a region at high risk of increased water hazards may lead to both international tensions and decreases in human security. To evaluate the adaptive capacity of transboundary river basins in the Mediterranean, the Middle East and the Sahel, this study draws from research on international environmental cooperation to develop a framework of transboundary adaptive capacity. The characteristics included in the framework are translated into measurable indicators and calculated for each of the 42 basins in the study area.