This paper addresses the predictive value for performance in medical school of undergraduate grades, the Medical College Admission Test (MCAT), information on the selectivity of the undergraduate institution, and selected transcript data. The performance data examined were basic science grades; clinical science grades; scores on National Board of Medical Examiners examinations, Parts I, II, and III; and information on academic difficulty. Methodological sources of differences in validity data, including restriction in range, criterion attenuation, and method specificity, are discussed. Reported validity data affirm the substantial value of traditional academic predictors of performance in medical school. Selection committees should, nevertheless, supplement academic data with nonacademic and interview information. Their inclusion is particularly important for minority and disadvantaged applicants. Medical schools should assess the validity of their selection systems. Additional research on the relations between academic predictors and performance-based indexes of clinical competence and on the role of traditional predictors with regard to the recently declining medical school applicant pool is suggested.