Since 2002, the rules and regulations of the No Child Left Behind (NCLB) Act have dictated state and local education policy, influenced state and local reform efforts, and led to significant investments in building the capacity of state and local education agencies to meet its mandates. Using a nationally comprehensive data set on school- and student subgroup-level NCLB outcomes, these three studies are the first national studies exploring the ways in which state officials’ interpretations of NCLB policy led to significant cross-state variation in school and subgroup outcomes across the country. I also investigate the extent to which NCLB accountability pressures and incentive structures led state and local officials to use school closure as a remedy for schools’ persistence poor performance. I conduct the latter analysis for all U.S. public schools and separately for a subset of U.S. public schools, all U.S. charters schools, in order to account for the idiosyncrasies of charter school governance and oversight. I find that significant cross-state variation in the share of schools identified as “failing” according to NCLB rules can largely be explained by variation in states’ NCLB implementation decisions, and that schools determined to have “failed” according to NCLB rules are more likely to close than schools that never “failed.” For all public schools and for charter schools only, a school determined to have “failed” according to NCLB rules is significantly more likely to close than a school determined to have never “failed.” Combined, these studies provide insight into the ways in which states’ NCLB implementation decisions had significant and lasting impact on school outcomes and state and local reforms.