An experimental course for third-year medical students, held at Columbia University, was aimed at enlisting larger numbers of future clinicians in the identification of public health problems and the development of nonclinical interventions, such as environmental and health education strategies. The course sought to develop a new perspective for the analysis of clinical observations. Students chose clinical problems, identified factors influencing incidence or prevalence, or both, and devised intervention strategies while working in a district of the New York City Department of Health. Students found that they could carry out their responsibilities only by going beyond the limitations of care for individual patients and clinical medicine. Students' perceptions and behaviour were measured during periods of their clinical training. Those who had taken the experimental course perceived public health problems and suggested and took corrective actions much more frequently than students in control groups.