One hundred 9th-grade students were divided into four groups of 25 each through systematic sampling procedures. Each of the groups were tested, pre and post, by the Otis-Lennon Mental Ability Test, forms J and K. During the pretest for all groups, the background condition of silence was observed. During the posttest, one group was again tested in silence. The other three groups were each tested to one of three background conditions: pop music, hard rock music, and soft rock music. Pop music played was characterized as more mellow, more melodic, and less intense than rock music. Hard rock music played was characterized as the most intense form with the hardest-driving beat, as well as being the least melodic form of the three. Soft rock music played was characterized as similar to hard rock but somewhat less intense and hard-driving. A comparison was made, through a series of 12 t-tests, between pretest and posttest means of all subjects, all male subjects, all female subjects, and each of the four groups – intact, males only, and females only. No significant differences in mean scores were found at the .01 or .05 levels of significance. The only two groups whose mean scores approached significance were the groups that listened to pop music and the males only from the pop music group. Lower posttest scores for certain individuals were noted. More of these were found in the group that listened to pop music than in any other group.