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 (pre-K) programs offered to children. In this study, I use 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 pre-K was already established in San Francisco, making this study a comparison of pre-K 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 the gains are larger for minority children. TK, however, had little effect on the rate of absences in kindergarten and first grade.