This study determined if overall mathematics performance of male and female students was: (1) different within each of six content areas; (2) differentially affected by ability grouping within each of the six content areas; and (3) differentially affected by the combination of ability grouping and grade level within each of the six content areas. Subjects were 963 students from grade 3 (N=241), grade 4 (N=245), grade 5 (N=260), and grade 6 (N=217). All subjects took a 45-item, multiple-choice test measuring concepts in six categories: numeration and number systems; equations and inequalities; whole numbers; fractions; decimals, currency, and percent; and geometry and measurement. Results indicate significant differences (favoring males) in three of the content areas: numeration and number systems; decimals, currency and percent; and geometry and measurement. A significant sex by ability effect was found only for geometry and measurement. Females performed better than males for low ability students; males performed better than females for high ability students. Sex by grade effect was not demonstrated to be significant for any of the six areas. These results are consistent with research findings indicating that when sex differences are found they favor males. (JN)