On Wednesday, August 18, 2021, Mathematica provided the DC State Board of Education with testimony that highlighted how the DC School reforms of 2007 impacted student achievement. The public comments served to clarify how the reforms, which led to mayoral control over the DC Public Schools, centralized authority over charter public schools, and a united enrollment system, improved student learning in math and reading. The insights presented were based on nearly a quarter century of data (from the early 1990s to 2017) from the National Assessment of Educational Progress, a national student assessment test that has been administered nationally every few years since the early 1990s, along with advanced statistical methods, which were used to account for pre-reform differences between DC and other areas and general trends afterward.