In the current study, we investigate two salient approaches available to policymakers that may improve preschool participants' instructional experiences in elementary school. The first involves advanced and challenging instruction in kindergarten and first grade, because children who attend preschool will hypothetically benefit more from advanced content. The other involves some type of professional support in which preschool teachers interact with their kindergarten and first grade counterparts to develop a seamless transition from one grade to the next. We use two experimental studies of preschool interventions and children's elementary school environments to examine whether the quality of instructional content or providing professional development supports to early grade teachers moderate the impacts of two well-known programs on children's cognitive skills: Head Start and Building Blocks. (author abstract)