There is a large literature that reviews the different regulatory models in use globally. While a detailed description of these models is outside the scope of this report, this chapter focuses on describing the main regulatory models for water services. It identifies the establishment of dedicated regulatory bodies as a growing trend among countries and sheds some light on the motivations behind this trend. One recent trend, the development of dedicated regulatory bodies for drinking water and wastewater services (WWS), stands out as a consistent response to some of the challenges to regulating water services (including the fragmentation of roles and responsibilities in the sector and the difficult political economy of tariff setting).