The sustainability of rural water supply and sanitation projects has long been of concern to those working in the sector. Despite continued large-scale investments by governments and international donor agencies, there is widespread evidence to suggest that after a number of years of operation, or less in some cases, many rural systems will face a variety of problems; these can include technical failures as well as financial or management challenges. Over past years, Aguaconsult has provided a number of inputs to USAIDs Environmental Health Project (EHP) related to the creation of institutional support mechanisms for community-managed rural water supply and sanitation services in Latin America and the Caribbean. The basic premise of these activities is that most rural communities need some ongoing support after systems are constructed in order to assure sustainability. This support will vary by community and will decrease over time as communities become more self-sufficient. This support covers a range of areas including technical backup, financial management, sanitation and hygiene, environmental protection, or management. In 2002 Aguaconsult was invited to work together with EHP in drawing together lessons from these experiences, to analyse the main models which have been applied in practice and to capture some of the key characteristics and factors influencing the design of institutional support mechanisms. The result of this process was the research and publication of a document providing guidance to organisations and individuals involved in the design and establishment of support mechanisms. Drawing on lessons from a review of existing examples, the document provides a framework for the establishment of such support mechanisms, explores key issues to be taken into consideration and includes a range of potential institutional models. In addition, the document can be considered as a resource tool to support advocacy efforts in highlighting the problem of sustainability and to raise awareness amongst key actors, including the major policy and donor agencies, about the importance of post-project support to communities.