Objective: To examine the role that social, behavioral and evaluation research played in a 6-year global HIV prevention program working in 45 developing countries. Methods: Computerized review of project database inventories: 320 research abstracts, 591 subproject abstracts, on-line literature search of project peer-reviewed literature, and hand review of 390 final project reports and country evaluations. Design: Research included descriptive, correlational, ethnographic, survey, quasi-experimental and experimental designs. Results: Over 400 social, behavioral and evaluation studies were conducted and consisted of program-related research, controlled intervention research and multi-year competitive research grants to advance the science of HIV prevention. Program research involved extensive use of qualitative methodologies and the development of innovative research tools such as rapid ethnographic assessments, behavioral surveillance surveys, and targeted intervention research. Intervention studies and multilevel evaluations of prevention programs in 19 countries demonstrated that HIV prevention has changed knowledge, attitudes, and behavior in target groups. Triangulating the results of a variety of data sources and methodologies, and increasing reliance on surveillance of behavioral trends among targeted population groups helped to circumvent numerous methodological problems. Conclusion: Linking research to program interventions is a critical component of effective HIV prevention but operationalizing the linking process remains a major challenge. (C) 1998 Lippincott Williams & Wilkins.