Efforts to redesign education in ambulatory settings are hampered by a lack of rigorous and coherent research on the learning process in these settings and the desired outcomes of the educational experiences. The authors present 13 priority research topics and 51 important research questions concerning education in ambulatory settings that were defined by a distinguished group of medical educators, clinicians, and policymakers who attended an invitational conference on education in ambulatory settings in 1996. The need to establish valid and reliable measures of quality and outcomes of educational programs and instructional interventions stood out as the major prerequisite for conducting research on education in ambulatory settings. Issues of theory building, research priorities, and research design are discussed, and policy recommendations are made for the development of valid measures of educational outcomes. The creation of a "Medical Education Outcomes Commission" is proposed to act as a repository for measures and instruments, and to provide the field with mechanism to validate instruments and uniform recommendations to conduct studies of quality. The authors urge funding agencies with missions that support medical education to invest in basic research on the outcomes of education in ambulatory settings.