Many women curtail their employment or stop work altogether to provide essential care to children and adults with care needs. Using Urban’s Dynamic Simulation of Income Model, we project that the employment-related costs for mothers of providing unpaid care average $295,000 over a lifetime. Eighty percent of these costs results directly from lost lifetime earnings, which average $237,000, 15 percent of what we project mothers would earn, on average, if they did not provide family care. The remaining 20 percent of lifetime costs results from lost retirement income from Social Security and employment-based retirement plans, which average $58,000 over a lifetime. These findings highlight the importance of caregiver supports, such as affordable childcare, for women with young children.