In many parts of the world water resources traverse political boundaries. The sustainable management of these transboundary water resources by necessity requires regional cooperation among riparian states. Coupled with physical water scarcity is increasing demand for water by growing populations and expanding economic sectors. In regions in which political relations are fragile, these tensions can prevent the establishment of a lasting peace or even erupt into active conflict.In the proposed IRSES program, we will study the Jordan River basin, shared by Jordan, Israel, and the Palestinian Authority, and the Guadiana River basin, shared by Portugal and Spain. The objective of this program is to provide a scientific forum for the establishment of a common ground for these basins as case studies of conflict and cooperation in river basin management and to identify the principles and mechanisms that both promote and hinder cooperation. Lessons learned from this project can be applied to other transboundary river basins in Europe and throughout the world.The partners include: Arava Institute for Environmental Studies, Center for Transboundary Water Research; University of Oxford, Wadham College; University Nova of Lisbon, Research Centre e-GEO; Masar Center, Jordan; Palestinian Wastewater Engineers Group; University of Sevilla, GIEST (Territorial Structures and Systems Research Group). These partners have a history of collaboration even when regional political tensions are high.Activities include exchange of Early Stage Researchers, visits from Experienced Researchers, and conferences and workshops for partners and for stakeholders. Dissemination to stakeholders is an important component of the program. The exchanges will be based on existing research projects that will be expanded to include a trans-European dimension.