While water is an increasingly scarce resource, most existing methods to allocate it are neither economically nor environmentally efficient. In these circumstances, water markets offer developed countries a form of regulatory response capable of overcoming many of the shortcomings of current water management. The debate on water markets is, however, a polarized one. This is mostly a result of the misunderstanding of the roles played by governments in water markets. Proponents mistakenly portrayed them as leaving governments, for the most part, out of the picture. Opponents, in turn, understand commodification of water and administration by public agencies as incompatible. Casado Pérez argues that both sides of the debate overlook that water markets require a deeper and more varied governmental intervention than markets for other goods. Drawing on economic theories of regulation based on market failure, she explains the different roles governments should play to ensure a well-functioning water market, and concludes that only the visible hand of governments can ensure the success of water markets. Casado Pérez proves her case by examining case studies of California and Spain to assess the success of their water markets. She explores why water markets were more extensively institutionalized in California than in Spain in the first ten years since their introduction and how the role of governments in each case study impacted water market operation. This unique analysis of governmental roles in water markets, alongside qualitative studies of California and Spain, offers valuable guidance to understand environmental markets and to face the challenges presented by water management in regions with periodical droughts.