The development of gender role qualities (attitudes, personality, leisure activities) from middle childhood to early adolescence was studied to determine whether siblings' gender role qualities predicted those of their sisters and brothers. Participants were 198 firstborn and second-born siblings (Ms = 10 years 9 months and 8 years 3 months, respectively, in Year 1) and their parents. Families were interviewed annually for 3 years. Firstborn siblings' qualities in Year 1 predicted second-born children's qualities in Year 3 when both parent and child qualities in Year 1 were controlled, a pattern consistent with a social learning model of sibling influence. Parental influence was more evident and sibling influence less evident in predicting firstborns' qualities; for firstborns, sibling influences suggested a de-identification process.