The effect of child care regulations on outcomes in the child care market and the labor market for mothers of young children is examined. The analysis uses a time series of cross sections and examines the robustness of previous cross-section findings to controls for state-level heterogeneity. Child care regulations as a group have statistically significant effects on most outcomes, with or without state fixed effects. However, regulations do not vary enough within state over time to allow precise identification of most individual regulation effects. The great majority of estimated regulation effects in all specifications are small and insignificantly different from 0. Some of the estimated effects seem reasonable in sign and magnitude, but others are clearly implausible. (Contains 5 tables and 20 footnotes.)