A growing body of research provides evidence that quality early childhood experiences can affect a host of life outcomes. Equally well documented is the variation in the quality of prekindergarten programs (pre-K) offered to children. In this study I employ a fuzzy regression discontinuity approach to evaluate the efficacy of Transitional Kindergarten (TK) on student outcomes in the San Francisco Unified School District. TK is a highly regulated, state funded, early education program. Importantly, universal prekindergarten was already established in San Francisco, making this study a comparison of prekindergarten opportunities. This study tests whether a more highly regulated pre-K program, situated solely in schools, can provide benefits to young five year olds over a modern, robust universal pre-K market. I find that students who attended TK outperform their peers on a variety of foundational literacy skills, with some evidence that the gains are larger for minority children. TK, however, had little effect on the rate of absences in kindergarten and first grade. (author abstract)