Five groups of medical schools are used to describe the relationship between the type of institution where a physician serves as a full-time faculty member and the type of institution where the M.D. degree was awarded. For each group of schools, percentage distributions are presented showing where the graduates now teach full time. The educational origins of all U.S.-trained full-time M.D. faculty members in each group are also shown in percentage distributions. These distributions are presented including and excluding individuals who are faculty members at the same schools where the M.D. was earned. Research schools are seen to contribute proportionally more of their graduates to U.S. faculties in all groups of schools. The group with proportionally more students oriented toward primary care specialties contributes faculty members largely to other schools in the same group. Research schools also evidence a similar "group breeding." All groups are net contributors to faculties at medical schools founded after the mid-1960s.