This literature review provides a review of policies, programs, and practices that have the potential to help students sustain the positive effects of preschool as they progress from kindergarten through grade 3 (K-3). The U.S. Department of Education's Policy and Program Studies Service commissioned this systematic literature review, which focuses on two specific approaches: (1) preschool and K-3 alignment; and (2) differentiated instruction in kindergarten and first grade. [For the "Results in Brief," see ED613464.]