Solving conflictual environmental policy problems is increasingly falling under the purview of local governments and public agencies. Nonregulatory approaches, such as the development of voluntary environmental programs (VEPs), could offer a useful policy alternative as they often have greater political traction and flexibility. However, there has been little work examining the use of VEPs in the public sector. This article uses a new dataset from California to examine how political institutions affect decisions by local governments and public agencies to participate in a voluntary urban water conservation program and whether this program has improved the water conservation performance of its members. The results show that special district governments, private utilities, and water suppliers dependent on purchased water are more likely to participate in the program and to join early. However, urban water agencies that have joined the program have not reduced their per capita water use more than those that have not. These results underscore the influence of political institutions in public-sector decision making and demonstrate that, as in the private sector, commitment to a VEP by local government and public agencies does not guarantee implementation or environmental improvements. While voluntary programs offer political and administrative advantages, in order for VEPs in the public sector to be effective they must be accompanied and supported by credible enforcement mechanisms, performance standards, and rigorous monitoring programs.