This paper studies how a potential policy change that raises women’s social security eligibility age from 50 to 60 would affect women’s employment, human capital, and earnings in China. I develop a dynamic model of female labor supply, featuring voluntary retirement; occupational choice; human capital accumulation contingent on occupation, age, and employment status; and child care using time inputs from parents, grandparents, and formal child care from the market. I estimate the model parameters by matching moments on employment, wages, and the time allocation of child care from micro data in China. The policy counterfactual raising women’s social security eligibility age yields two main findings. First, the policy change leads to only a moderate increase in aggregate labor supply because it affects the employment of old and young women in opposite directions. The reduction in social security insurance encourages women above the age of 50 to supply more labor. Yet low-skilled young women with children reduce their labor supply in response to the children’s grandmothers working more and providing less child care. Second, since human capital accumulation is faster on the earlier career path rather than later, the reduction in early career employment leads to persistent losses in human capital and earnings for low-skilled women.