Final evaluation of an onsite environmental sanitation program (7/95-7/97) implemented as part of a Housing Guaranty Project in two peri-urban communities in Montego Bay, Jamaica. the Sanitation Support Unit (SSU) of the Construction Resource and Development Center (CRDC), a Jamaican NGO, was the implementing agency. CRDC/SSU developed technical and behavioral change strategies that significantly increased sanitary coverage and improved urban environmental conditions. the technical strategy developed technologies that were both appropriate for site conditions and acceptable to individual lot holders, used private sector contractors for construction, and provided affordable solutions to environmental problems. It is estimated that, by the end of the project, 620 families will be using new or improved sanitary facilities. in addition, the project has reduced the flow or seepage of untreated wastewater through sinkholes into Montego Bay by an estimated 3,420 gallons per day. "New" untreated wastewater is also being prevented from entering the Bay; approximately 14,820 gallons of sewage per day are currently being disposed of in an environmentally acceptable manner. the behavioral change strategy, which complemented the technical strategy, was also successful. A comparison of baseline and monitoring results showed substantial improvement in hygiene behaviors, especially in two of the behaviors considered most effective in preventing diarrheal diseases: hand washing and protection of drinking water. in addition, behaviors were significantly changed not only by the presence of acceptable latrines, but also in usage of latrines by all family members over 5 years of age (a more valuable measure of hygiene). With training in participatory methods, the program made effective use of carefully selected individuals to sensitize others in their community to environmental conditions and to facilitate their ability to make informed choices regarding sanitation and healthy behaviors. Women have played an active role in the program as opinion leaders and promoters of positive health behaviors. A key success of the program was providing community members the opportunity to secure loans to finance sanitary improvements that reduce environmental pollution and promote healthy living in their households and neighborhoods. A considerable number of families assisted are headed by women. Finally, the CRDC's SSU office in Montego Bay has become financially self-sufficient and institutionally sustainable. in sum, the project was an excellent example of how an NGO can play a significant role in implementing a sanitation program. the program itself demonstrated an effective model for providing basic urban environmental services to families living in poor peri-urban areas of Jamaica and could be replicated by CRDC in similar peri-urban areas throughout Jamaica if credit were to be made available to households for the construction of sanitary solutions. Replication efforts should bear in mind the factors that made the project a success: involvement of the community in decision-making; creation of demand for better sanitation; teamwork between SSU's community officers and technical officers; effective monitoring; flexibility in implementation; integration of hardware and software approaches; provision of capital financing for hardware; charging of fees for services rendered; having SSU serve as facilitator rather than as implementer; and reception of CRDC/SSU of effective and consistent TA from international experts.