This article focuses on a comparison of states and markets in the management of transboundary water. Borders are often harbingers of change and areas of innovation. Nation states have struggled mightily to overcome problems of shared river basins and aquifers. Today, the state-centric model is losing its hegemony. Once the article has established the limitations of states as governing institutions, its attention turns to an alternative offered by public choice scholars. Proposals for functional, overlapping, and competing jurisdictions are subjected to critical scrutiny and found wanting. Both of these conceptual frameworks have serious flaws. While the state-centered model poorly captures the emerging complexities of intermestic politics, the market approach fails to incorporate institutions that foster intersectoral cooperation and communication. The article concludes that effective governance of fluid resources is increasingly and necessarily founded on the cooperative interrelationships of various institutions that represent the variety of complementing logics and functions within the transnational water arena.