There is an increasing focus on the international politics and security surrounding internationally shared waters. However, the global literature on transboundary waters does not have a single accepted definition of transboundary water cooperation and complications can arise when multiple understandings are used. For example, cooperative efforts over shared waters can take many forms; place matters in the development and continuation of cooperation between riparians. Climate, hydrology, socio-political environments, and particularly political-will play a role in establishing and maintaining cooperation. The goals and outcomes of transboundary water cooperation can change depending on the definition and understanding of cooperation. One common aim is that cooperation should be effective, but effectiveness has an equally variable definition as transboundary water cooperation. This presentation dives into these challenges and presents a model for defining cooperation, as well as a method to evaluate its effectiveness.