This statement provides a summary of what is currently known about how state and district pre-k programs affect children's learning immediately after program completion and into the elementary grades. We begin by reviewing the scientific evidence about early child development in the years before children experience pre-k, the varied experiences across pre-k classrooms, and what happens after pre-k when children enter elementary school. Only by placing the pre-k year in the developmental context of what comes before and after can we understand what to expect from pre-k programs and why. Next, we review the evaluation studies of the immediate and longer-run effects of pre-k by summarizing findings and explaining their implications for policy and practice. Because most of the graduates of today's pre-k programs are still young and program evaluations are continuing, these findings, like pre-k itself, are a work in progress. (author abstract)