The Global Environment Facility (GEF) aims to assist countries in better understanding the functioning of their international water systems and developing an appreciation of how sectoral activities have an impact on the environment. By funding the transaction costs of the learning processes necessary to gain a better understanding of these ecosystems, the GEF hopes countries will collaborate with their neighbors to reach effective solutions collectively. This paper explores lessons learned from GEF efforts concerning trans-boundary water resources. It investigates GEF efforts in (1) creating a shared vision, (2) involving the public and private sectors, (3) coordinating program activities, (4) building governance institutions and capacity, and (5) improving the ecosystem. These lessons reveal relative success in creating a shared vision and building governance institutions and capacity for trans-boundary waters but uncovers significant obstacles in the other areas.