Substantially reducing the number of human beings who lack access to clean water and safe sanitation is one of the key Millennium Development Goals. This book argues and demonstrates that this can only be achieved by a better integration of the technical and social science approaches in the search for improved organization and delivery of these essential services. It presents a historical analysis of the development of water and sanitation services in both developed and developing countries, which provides valuable lessons for overcoming the obstacles facing the universalization of these services.