Many argue that childcare costs limit the labor supply of mothers, though existing evidence has been mixed. Using a child’s eligibility for public kindergarten in a regression discontinuity instrumental variables framework, I estimate how use of a particular subsidy, public school, affects maternal labor supply. I find public school enrollment increases only the employment of single mothers without additional young children. I compare this result to previous work, focusing on striking increases in a similar setting but earlier period (Gelabch 2002). Differences in the population of mothers, labor supply, and patterns of lifecycle events likely drive the discrepancy in results.