Data from a sample of 2,593 high school seniors (58% female) were used to study the relationship between courses taken and scores on the American College Testing (ACT) English Usage Test, the ACT Mathematics Usage Test, the ACT Social Studies Reading Test, and the ACT Natural Sciences Reading Test. For English and Mathematics, test performance tended to be higher with a higher number of relevant courses taken. For social studies, the picture was less clear, with courses in History and Economics appearing helpful. Many factors contributed to scores in Science, but test performance was related to courses taken. Numerous tables provide descriptive data for correlations by subject. (SLD)