Purpose: This systematic review aimed at identifying, categorizing, and analyzing peer-reviewed literature on organized before- and after-school (B&ASP) physical activity programs from 2000 to 2020. Methods: We analyzed 291 articles that fit the inclusion criteria from five databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses Guidelines were followed. Results: Research on B&ASPs has increased and been published in 157 journals across 26 countries. Most studies were quantitative. Most studies used a theoretical or conceptual framework and reported reliability, validity, and trustworthiness. Varied additional foci of impact were reported through different physical activities. However, physical activity was usually not measured. Interventions were 1-520 weeks long and conducted in different study contexts. Many studies targeted marginalized groups but did not utilize critical theory. Conclusion: Further studies should aim to better understand the nuances of B&ASPs, and critical theories could be useful. The lack of journals for B&ASP research limits scholars' ability to move the field forward.