Aptitude test scores have been correlated with grades in twenty-six courses and with overall indices of academic performance, based on over 500 students attending a public high school. There is little evidence of differential validity for the major academic subject areas; instead, five tests (English Vocabulary, Graphoria, Silograms, Analytical Reasoning, and Ideaphoria) tend to be most highly correlated with grades, and the latter four of these tests remain relatively highly correlated with grades after Vocabulary is controlled through partial correlation. Other aptitude tests correlate highly with some of the more specialized courses. (Author)