Using data from a 2-year longitudinal study of 200 Black and White adolescent girls (mean age was 13.8 years at study entry), the authors investigated the implications of differences in body fat for dating and sexual activity and the implications of heterosexual activity for dieting and weight concerns. Among White girls, and Black girls with college-educated mothers, more body fat was associated with a lower probability of dating, even among nonobese girls. However, dating and sexual experience were unrelated to subsequent dieting and weight concerns. For both Blacks and Whites, body fat was the key determinant of dieting, weight dissatisfaction, and eating concerns. These findings indicate that adolescent girls' concerns about weight have a basis in real experiential differences, and efforts to promote healthy attitudes and eating habits may be more effective if the experiential implications of weight differences are taken into account.