The importance of considering water and sanitation in the peri-urban interface of metropolitan areas and regions arises from the fact that there are social, economic, environmental and institutional interactions between urban and rural areas which are captured in this interface. It is here where many of the processes of change in urban-rural flows take place, leading both to problems and to opportunities not only for peri-urban communities but also for the sustainable development of adjacent rural and urban systems. Focusing on the peri-urban interface of five metropolitan regions in Mexico, India, Tanzania, Egypt and Venezuela, this three-year project funded by DFID examined the disjuncture between policy-driven arrangements to improve service delivery and the actual needs-driven practices deployed by poor women and men in these areas.