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 a large, urban district in California. Importantly, universal prekindergarten was already established in the city which the district serves, making this study a comparison of different prekindergarten opportunities. TK is a highly regulated, state funded, early education program meant to provide a more developmentally appropriate kindergarten curriculum. This study is a test of whether a more highly regulated and academically oriented pre-K program can provide benefits over a more traditional pre-K approach for young five year olds. I find that students who attended TK outperform their peers on a variety of foundational literacy skills. In addition I find some evidence that the gains are larger for minority children.