This study investigated gender differences on the ACT English and mathematics scores by controlling both high school course taking patterns and high school subject matter course grades. A sample of 5100 ACT test takers (44% male) from the 1989-1990 academic year was selected for this study. Data were analyzed separately for juniors and seniors. Analyses of variance using the general linear model were employed to deal with disproportional cell frequencies. The gender differences favoring males on the mathematics scores were most pronounced for those having moderate math backgrounds, but differences favored junior females who had full math backgrounds. The findings were discussed in terms of the results and designs of previous studies of gender differences on admission test scores. (Contains 16 references and 7 tables.) (Author)