Review of existing monitoring and evaluation (M&E) efforts for MDG Water Supply and Sanitation with the objective of mapping existing efforts, identifying challenges that need to be addressed and making recommendations for further action. The authors mention three relevant examples of complementary monitoring approaches that can enhance monitoring by providing innovative approaches to sampling, data analysis and survey conceptualisation: Vision 21 monitoring, the Method of Participatory Assessment (MPA), and country monitoring by Water Aid. Based on the achievements of MDG monitoring for water supply and sanitation and the challenges, a number of recommendations for action have been formulated taking into account the interdependence of different challenges and points of entry. These recommendations attempt to balance a demand for comparability and uniformity with the need for flexibility given the number of actors, institutions and countries involved. The recommendations can be grouped into the following three categories: A. Strengthening statistical capacities and monitoring effectiveness; B. Coordination, Information Sharing and Cooperation; and C. Strengthening Global Monitoring and the JMP in particular.