Background: This article describes community-based, student-run health fairs and discusses how students learn, through a variety of processes, strategies for patient education, prevention, and community service. Description: Medical student volunteers organize themselves into committees and spend the year prior to each fair addressing the logistics, financing, publicity, and training required for a community-based health fair. On the day of the fair, students provide an array of patient education, health promotion, and health screening services. Later, students return to a follow-up fair to review with patients results of laboratory studies. Evaluation: In 1997, two hundred thirteen 1st- and 2nd-year students and 18 voluntary faculty provided health education and preventive services to 703 patients, including 450 blood pressure checks, 203 vision screenings, 71 Pap smears and breast exams, and 77 immunizations. Patient satisfaction was high: 93% of patients rated the experience as good or excellent. Conclusion: The health fair mode has proven to be an excellent way to teach clinical, organizational, patient education, and preventive medicine skills to 1st- and 2nd-year students. The methodology relies heavily on service learning, peer teaching, and learning through responsibility.