This study sought to determine if participation as a musician or an athlete had an effect on academic achievement as measured by standardized test scores. It was hypothesized that students who received training as musicians would score higher on the core battery composite of reading, language, and mathematics sections of the California Achievement Test than their athletic and non-musician peers, and that the amount of time spent (years of music study or athletic participation) would have a significant effect on test scores. Subjects were 346 students who performed in the band or the choir, were athletes, or were nonparticipants in either music or athletics. Data were collected from 1991 through 1995 (grades 5 through 9). Results show that although the mean scores for musicians were higher than nonmusicians/nonathletes, participation in music was not a conclusive factor in predicting statistically higher academic scores than those of nonmusicians and nonathletes. Musicians did score higher than the athletes did, and over time this gap widened. Findings indicate that factors other than enrollment in a performing music class were affecting the outcome. The schools represented in this study reflected a cross section of different types of music programs. Results also indicated an overall drop in standardized test scores in the ninth grade that was not seen for student musicians. Two appendixes contain data tables for the study. (Contains 9 tables and 41 references.) (SLD)