The Evaluating Children’s Physical Activity in School-Based Programs study is evaluating several physical activity (PA) programs operating in Boston public schools. Using a mixed-methods approach, including surveys and interviews with program staff and leadership, this research will advance understanding of the amount of PA such programs provide, as well as whether they reach schools equitably based on factors like student race-ethnicity and socioeconomic status. It is also exploring the influence of the COVID-19 pandemic on such PA programs, including their reach, effectiveness, and implementation practices, as well as how those impacts might persist into the future.