This study focuses on clarifying factors that influence the sustainability of a development project, by examining a bilateral aid project in Vietnam: "The HIV/AIDS/STI Commune Clinics Network Project." This is a CIDA funded project which started in 2003 and is still going on. The purpose of this project is to diagnose, treat, and prevent STIs/HIV/AIDS in a vulnerable population, using a new etiological approach. The methodology applied in this study was a qualitative approach, with in-depth interviews used as the key means of data collection. The research questions emphasized factors that are useful to anticipate the possibility and reality of the project's sustainability, when foreign funding ends. Also how staffing issues and the quality of the services would impact on the sustainability of the process. Data collected show that the continued, future application of an etiological approach to STI treatment, which is being used in this CIDA project, remains questionable when foreign support ends. However, data analysis will provide the prospect for sustainability of the project, and my major findings, discussions, recommendations and conclusions will support the clarification of the research questions. In summary, factors that influence the sustainability of the HCCN project, including government commitments, staffing assignments, quality of services and etiological approach, are the main concerns of this study which can be found throughout this study.