This research project focuses on the socialization of young women, and whether that socialization is affected by the sex of the siblings with whom a girl is reared. Specifically, it is argued that sex role differentiation will be stronger when the family includes both male and female children. Subjects were 939 women, 14 to 24 years of age, who were surveyed for the National Longitudinal Study of the Labor Market Experience of Young Women. Subjects were interviewed in 1968 and re-interviewed in each of the next four years (1969-1972). Socialization effects were examined in terms of two factors: the subject's own educational aspirations as reported at two points in time (1969 and 1972), and her reports of her parents' goal for her education and the amount of encouragement they gave her to pursue post-high school education. Respondents were also asked about their total number of siblings, their birth order, and the siblings' ages and educational attainment. Subjects were classified into four categories: Only Child, Sisters Only, 1+ Brothers, or Unknown. Results indicated weak confirmation of the hypothesis. (Author/SS)