This study compares the characteristics of the practices and patients of recent graduates of family practice and general internal medicine residency programs. National samples of 104 family physicians and 134 general internists completed questionnaires and provided log-diary data for more than 7,500 office visits and 1,100 hospitalized patients. Family physicians and general internists were generally similar in demographic and practice characteristics, though family physicians were more likely to have entered office-based practice (90% versus 70%). Among office-based physicians, family physicians saw more patients per week in ambulatory settings (117.3 versus 74.6), whereas general internists had more patients in the hospital (6.45 versus 3.81) and provided more hospital consultations per week (2.74 versus 0.45). Family physicians practiced in smaller communities and were more likely to practice on Saturday mornings, to accept walk-in patients, and to schedule appointments for new patients within 1 week. Both specialties functioned as first-contact generalists for at least 95% of office encounters. Although pediatrics and obstetrics are practiced only by family physicians and general internists see proportionately more older patients, within specific age groups the patients of general internists and family physicians were similar in terms of their main health problems, functional status, and diagnoses.