In recent years there has been growing interest in early childhood programs as a policy tool for improving educational outcomes. While much of the current early childhood debates have focused on expanding and improving interventions that occur before children enter the K-12 system, recent work suggests that children’s experiences in their first years of elementary schools have meaningful and long lasting impacts on a host of outcomes. Using longitudinal, experimental data, for instance, Chetty et al (2011) demonstrate that high-quality kindergarten experiences are related to improved earnings, higher rates of college attendance, and increased levels of savings. In light of our heightened understanding of the importance of early elementary experiences, this panel includes three papers that examine the changing nature of kindergarten classrooms and explore the impact of these changes for student learning and for achievement gaps. Since the first American kindergartens emerged in the 1850s there has been discussion about the purpose of kindergarten with stated goals ranging from child care for working mothers to a space for play, discovery and development of social skills. As accountability pressures within the K-12 system have mounted, there has been anecdotal accounts of kindergarten shifting into an increasingly rigorous and academic experience. Bassok & Rorem document this trend empirically, showing tremendous shifts in kindergarten time-use between 1998 and 2006. They use several difference-in-difference approaches to estimate the causal impact of the No Child Left Behind Act (NCLB) on the kindergarten experience. They find that kindergarten curriculum and time use, in the post-NCLB era mirror first grade classrooms in the pre-NCLB period. There is substantial debate about the impact of this shift on the experiences of young children. Although some critics warn that young children are not developmentally prepared for the intensification of kindergarten, others argue that kindergarteners, particularly those from low-income and minority groups, could benefit substantially from high quality and developmentally appropriate pre-academic curriculum. However, empirical evidence on effective strategies to support academic learning in early childhood classroom is currently lacking. Loeb & York fill this gap reporting on results from a multi-site, cluster-randomized trial in the San Francisco Unified School District (SFUSD), examining the effects of a formative literacy assessment on both student outcomes and teacher practices in pre-kindergarten through first grade classrooms. Although a large body of research has examined the impact of testing practices in the later elementary grades, this study fills a gap in our knowledge about the usefulness of assessment practices in the early elementary years. While changes in curricular focus and assessment strategies are one approach for increasing the academic content of early elementary classrooms. a related approach to kindergarten reform is extending the length of the kindergarten school day and/or school year. Nearly all children in the US participate in kindergarten, and the percentage participating in full-day programs has more than doubled since the early eighties. Gibbs provides new experimental and regression discontinuity evidence on the impacts of full-day kindergarten relative to half-day programs, and finds substantial impacts, particularly for Hispanic children.