The tragedy of the commons is a myth in water management. Hundreds of case studies of local water users devising institutional arrangements to successfully govern their use of shared water resources have been documented. Failures in water governance that have occurred are rarely due to the tragedy of the commons, that is, to the lack of institutional arrangements. Failures are more often due to the challenges of devising, adapting, and maintaining institutional arrangements in dynamic water settings. This chapter explores two institutional challenges that repeatedly confront water users-devising institutional arrangements that are well matched to the physical and social features of the water setting; and devising complementary and supportive relations among organizations and governments operating at different scales. The chapter begins with a review of the literature on common pool resources and the creation and maintenance of local, self-governing institutional arrangements illustrated through case studies of water governance. It then turns to an examination of cross-scale linkages - relations among organizations and governments at different scales, from the local to the international. The chapter provides an in-depth examination of cross-scale linkages, what appear to be the most important features of such linkages, and, in particular, important features of higher level governments that promote support for the self-governing efforts of local resource users. Cases of water governance from the USA and Spain are used to illustrate cross-scale linkages and the role they play in common pool resource management.