This longitudinal study of 200 young adolescent girls and boys (mean age 11.6 years in sixth grade) investigated the hypothesis that differences in masculinity, femininity, and sex role attitudes would intensify across the sixth, seventh, and eighth grades (between 11 and 13 years of age) and that pubertal timing (early, on time, late) would play a role in this intensification. Analyses revealed that sex differences in masculinity and sex role attitudes increased across grades, but not sex differences in femininity. Pubertal timing was not associated with this gender divergence, although the evidence is equivocal for boys. The results provide support for gender intensification, but the role of pubertal timing may not be as strong as previously supposed.