Combining eight years of panel data with an event study approach, this study shows that rural Chinese women's labor supply falls following the birth of a child. In contrast, men's labor supply does not fall after birth. Furthermore, a woman's labor supply falls more following the birth of a son than a daughter. Following the birth of a son relative to a daughter, household cigarette consumption declines, and a mother's leisure time, her prob ability of school enrollment, and her participation in decision-making increase. There are no increases in other investments in boys complementary to mothers' time, such as food expenditures, breastfeeding, or immunizations. These results are consistent with the idea that mothers are rewarded more for having a son, leading them to have more leisure and work less.