This research investigated the association between academic lineage and student performance in medical school. The purposes of the study were to: (1) determine whether the Carnegie classifications of medical school applicants' institutions of origin are associated with academic performance in medical school; (2) consider the relationship between the admission selectivity of the schools of origin and the academic performance of medical school students; (3) compare the performance of medical students from institutions under public governing control with students from privately controlled institutions; and (4) establish a model by which the relative academic strengths of applicants from a variety of undergraduate institutions can be understood more clearly based on the previous performance of medical students from schools with similar institutional characteristics. A review of the literature on medical school admissions was completed and used to develop this research. Medical students from the University of Texas Southwestern Medical Center at Dallas who enrolled between the years 1990 and 1994 and graduated or were dismissed between the years 1994 and 1998 were selected as the sample for the study (n=933). The undergraduate institution of origin for each student was coded based on its Carnegie classification, admissions selectivity group, and whether its governing control was public or private. Because the sample was not randomly selected and the data likely would not meet the assumptions of equal means and variance with the population, nonparametric analyses of variance and multiple comparison tests were completed to compare the groups of the independent variables over each dependent variable. The analyses revealed that for the sample of medical students selected for this study there was an association between academic lineage and student performance in medical school. Differences were found among Carnegie classifications on the dependent variables of cumulative medical school grade point average, class rank, failure rate, and score on Step 1 of the United States Medical Licensure Examination. Further, it was found that admission selectivity was also associated with student performance in medical school for each dependent variable except failure rate. Finally, the study results indicated no association between public or private governing control and student performance in medical school.