Objective.-To provide recommendations regarding the establishment and maintenance of school-based clinics, based on analysis of data from a clinic located in a New York City high school. Design.-Review of demographic, medical, and psychosocial data collected during student visits. Subjects.-During 2 1/2 years, 1283 students were seen. The students were 53% girls and 47% boys; 65% black and 25% Hispanic; and 65% grades 9-10 and 35% grades 11-12. Results.-There were 7920 visits. Visits were for acute or chronic medical problems (44%), physicaL examinations and immunizations (25%), gynecologic or sexuality-related issues (17%), and mental health concerns (14%). Psychosocial characteristics of the 378 students who enrolled during the 1989-1990 academic year indicated that only 27% lived with both natural parents, 55% were foreign-born, 37% had repeated a grade at least once, 44% were sexually active, 13% drank alcohol, and 14% had past or present suicidal ideation. Conclusions.-These data demonstrate that a school-based clinic can be involved in the management of a wide range of health care needs for large numbers of at-risk youth. In addition, school-based clinics can serve as a major site for the teaching of medical students and residents, and as a valuable resource for clinical research.