This document is intended to be an informational tool that helps project designers better understand and confront the problems in improving sanitation in peri-urban areas. It is not meant to be a technical design manual, nor is it a comprehensive reference document on existing technologies. The ultimate goals of the report are to provide the reader with some key questions to ask, with information to gather as part of the planning and design process, and with suggestions about what basic approach to follow in setting up peri-urban sanitation projects. Peri-urban areas present unique challenges to sanitation improvement activities. Most challenging are the characteristics that set these areas apart from the urban and rural sectors: poor site conditions, unreliable water availability, high population density, the heterogeneous nature of the population, and the lack of legal land tenure. These characteristics are much more complex than those typifying rural and formal urban areas. The "standard" technical and social solutions for low-cost sanitation currently used in rural communities are not necessarily appropriate for improving community sanitation in peri-urban areas. Conventionally, most community sanitation problem assessments and project design efforts focus on the technical feasibility of intervention options. Experience suggests that these technology intervention projects often fail to meet their objectives. The report suggests that the complexities of peri-urban settlements required that a more comprehensive interdisciplinary approach be used to clarify the problem before attempting to design a project that will address peri-urban community sanitation needs. This document reviews the key public health, environmental, social, financial, economic, legal, and institutional issues that many of these settlements face and must be understood before developing a program designed to improve a peri-urban community's sanitation services. to address these problems, the project designer must deal not only with engineers but also with legal specialists, financial analysts, social scientists, urban planners, and a wide range of institutions, such as the water and sanitation utility, the Ministry of Health, urban development authority, and the municipality. The document should be particularly useful for those project officers in A.I.D. and other international organizations who come to the urban sector with "generalist" experience, or with previous experience in providing water and sanitation in their developed countries or in rural areas of less developed countries. The paper also should be helpful for technical specialists who assist with project development, particularly in ensuring that they become aware of issues in a wide range of subject areas other than their specialty. The sanitation challenges peri-urban areas present are unique, and they demand that difficulties in providing appropriate excreta disposal systems be confronted head-on. in some "impossible situations," no technical solution will prove viable. to create new solutions, project leaders must challenge the status quo at the municipal and national levels of developing countries, which continue to deal with urban sanitation in a conventional way. By necessity or choice, in the foreseeable future, government institutions, bilateral and multilateral aid organizations, the engineering sector, and NGOs, all will be compelled to shift more of their attention and resources to the sanitation needs of peri-urban populations. (Author abstract)