This study investigates the determinants of labor force participation and child care utilization of mothers in the slums of Guatemala City. Data come from a survey in 1999 of 1,300 randomly selected mothers with preschool children, out of whom 37 percent worked for pay in the last 30 days. Results show that education, life cycle, and household demographic factors affect work and child care decisions. Higher household wealth reduces the mother’s chances of being in the labor force but does not significantly affect hours worked. The value of assets the mother brought to her marriage, however, increases the likelihood of working for pay. Fees and travel time for child care do not have significant influences on the type of child care used or mothers’ labor force participation, but hours worked decrease with higher formal day care prices. This suggests that interventions to reduce the price of formal day care in poor urban areas may have the potential to increase the labor hours of mothers residing in such neighborhoods.