Used in combination with other preadmissions indicators, MCAT scores continue to be an important tool of medical school admissions committees in the United States and Canada, helping them make decisions about who should be admitted into medical school. MCAT scores substantially supplement the ability of undergraduate GPAs to predict success in medical school (Julian, 2000a; Wiley & Koenig, 1996). As predictors of success in medical school, undergraduate GPAs alone explain approximately 29% of the variance in students’ grades in the first 2 years of medical college. Undergraduate GPAs also account for about 13% of the variance in medical school clerkship grades. When MCAT scores are combined with undergraduate GPAs, an additional 21% of the variance in grades in the first 2 years of medical school is explained, and the percentage of variance in the clerkship grades that is accounted for by the predictors more than doubles. MCAT scores alone are almost as effective in the prediction of United States Medical Licensure Examination scores as is the combination of MCAT scores and undergraduate GPAs.