This study reviews the experience of cooperation in five international river basins, focusing on the perceptions of risks and opportunities by country decision makers responding to a specific prospect of cooperation, and the effects of risk reduction and opportunity enhancement on the cooperation process. We explore the following five categories of risk: Capacity and Knowledge; Accountability and Voice; Sovereignty and Autonomy; Equity and Access; and Stability and Support. We surmise that risk perception plays a key and less understood role in decision-making processes over shared rivers cooperation, and conclude that countries and third parties can best achieve sustainable cooperation when long-term investments are made in risk reduction. We also point to areas for further study to better understand the motivations for cooperation.