This study examined the role that sex-related differences in the nature of the grade criterion and in variables associated with academic performance play in the over- and under-prediction of college grades by the Scholastic Aptitude Test (SAT) both when the test is used alone and in conjunction with high school grades. An entire freshman class (4,351 students) at a large state university was studied. Women's grade point average (GPA) was underpredicted, but only by a small amount. Adjusting the GPA for differences in grading standards for individual courses did not affect the underprediction, but controlling for sex differences in individual-difference variables concerned with academic preparation, studiousness, and attitudes about mathematics reduced or essentially eliminated the underprediction. Eight figures and 22 tables present results of the analysis. Two appendixes contain classifications and scores, and the study questionnaires. (Author/SLD)