This study examines student performance on the SAT and SAT Subject Tests in order to identify groups of students who score differently on these two tests, and to determine whether certain demographic groups score higher on one test compared to the other. Discrepancy scores were created to capture individuals' performance differences on the critical reading, mathematics, and writing sections of the SAT and selected Subject Tests that were deemed the most comparable (such as the SAT critical reading section and the Subject Test in Literature; the SAT mathematics section and the Mathematics Level 1 and Mathematics Level 2 Subject Tests). The percentage of students with discrepant scores was compared for each SAT-Subject Test pair, overall and by gender, racial/ethnic, and best spoken language subgroups. Next, the predictive validity of SAT and Subject Test scores for predicting first-year college/university grade point average (FYGPA) was compared for students with and without discrepant scores. The results demonstrate that the percentage of students with discrepant SAT and Subject Test scores is small, especially for the tests that are most similar in terms of content. The validity of the SAT and SAT Subject Tests for predicting FYGPA varies according to the assessment on which a student scored higher relative to the other, and the pattern of results varies for the different SAT-Subject Test pairs. In all cases, however, SAT and Subject Test scores each have incremental predictive power over the other. This study provides evidence that each test provides distinct information that may be useful in the college admission process. As such, joint consideration of these two test scores in college admission is warranted. Estimates of Standard Error of Difference (SED) and Effective Significance Levels is appended.