Developmental differences in children's self-perceptions of masculinity and femininity during the middle childhood period were investigated in English-speaking children from Grades 2-7 (N = 517). The majority of participants were Caucasian and from middle socioeconomic families. The multidimensionality of masculinity and femininity was also examined. The Children's Personal Attributes Questionnaire (CPAQ), a standardized self-report instrument, was used to assess masculinity (instrumentality) and femininity (socioemotional expressiveness). Developmental differences were found within a cross-sectional design, with a decrease in feminine responding and an increase in masculine responding. At the item level, however, both boys and girls were relatively selective and limited in the items that had a grade effect. Interestingly, greater symmetry was observed between boys' masculine and feminine scores than between girls' scores. Furthermore, fewer boys had predominantly masculine responding than girls had predominantly feminine responding. Factor analysis provided initial support for the presence of three factors-interpersonal orientation, leadership, and emotionality-which appear to have greater specificity and reflect more distinct subtraits than the original scales of the CPAQ. The results of the present study suggest that meaningful developmental changes occur during the middle childhood period, and that a single summary score for masculinity or femininity ignores variations in gender-typed subtraits and thus raises both scoring and interpretation concerns.