This paper estimates the causal effect of pre-kindergarten enrollment of children in the labor market outcomes of their mothers. I exploit a quasi-experimental setting in Peru, in which children turning 3 years old before March 31st are eligible to be formally enrolled in pre-kindergarten, while those who were born after April 1st have to wait an additional year. This leads to a large discontinuity in the probability of enrollment to pre-kindergarten. Using the child’s exact date of birth as an instrument for enrollment, I estimate that the complier mothers who enroll their children in pre-kindergarten at 3 years old are 44 percentage points more likely to work, than those whose children are not eligible for enrollment.