The authors add to and extend the emerging evidence base of the effects of public preschool programs on child school readiness. Using a quasi-experimental, Regression Discontinuity (RD) design, they estimate the impacts of a universal preschool program on children's early numeracy, language, literacy, and executive function skills, both for the overall population and for several subgroups. While they find impacts similar to those reported in other public prekindergarten RD studies, they make a unique contribution to the literature, as theirs is the first causal study of a universal prekindergarten program in which a uniform curricula was in place across the district and in which they have information about the type of care experienced by control children during the treatment year. At Society for Research on Educational Effectiveness, they will also present results from robustness checks new to this literature, including sensitivity of results to differential time to join and attrit from the intervention. (Contains 4 tables and 1 figure.)