Schools vary in their capacity to implement recommended strategies to prevent infectious diseases, such as COVID-19. Professional development (PD) and technical assistance (TA) are well-established tools used to strengthen school capacity and infrastructure for healthier school environments. The authors examined the relationship between PD and TA received by districts and schools and their implementation of COVID-19 prevention strategies during the 2020-2021 school year. We conducted a descriptive analysis of survey responses collected during Spring 2021 from selected districts and schools in 9 participating states. The survey assessed the implementation of 10 COVID-19 prevention strategies recommended by the Centers for Disease Control and Prevention and whether district or school staff received PD and/or TA on topics related to COVID-19 during the same year. Survey responses were received from designated contacts in 310 districts and 931 schools across 9 states. The dependent variable was the number of COVID-19 prevention strategies that were reported as "in place" by each district and school ranging from 0 to 10. On average, districts and schools reported implementing 7 of 10 recommended COVID-19 prevention strategies during the 2020-2021 school year. Schools that received PD on at least 1 of 12 topics reported implementing 7.61 COVID-19 prevention strategies, whereas schools that did not receive PD reported implementing 6.34 strategies. Similarly, schools that received TA on at least 1 topic reported higher COVID-19 implementation scores (7.51) than schools that did not receive any TA (7.20). Findings reveal a positive relationship between receiving PD and/or TA and implementation of COVID-19 prevention strategies in school settings.