This research reports the childhood antecedents of the sexual division of labor, analyzing the family chores and paid employment of 669 boys and girls aged 2–17. Data from a statewide random sample of parents show that sex typing begins very early in work roles and that, by the time children reach adolescence, sharp differences exist between “boys' work” and “girls' work.” multiple classification analysis indicates that family background characteristics and family structure have relatively little impact compared to sex and age of child as determinants of sex typing.