School-wide Positive Behavioral Interventions and Supports (SW-PBIS) is an evidence-based, multi-tiered framework designed to support all students across all school settings. The implementation of SW-PBIS is associated with improved student outcomes across elementary, middle, and high schools. For high schools especially, the implementation of SW-PBIS is associated with reductions in student dropouts, office discipline referrals, the numbers of students needing more intensive supports, as well as increased student attendance. Although the number of schools adopting SW-PBIS continues to increase in the U.S., the rates of high schools adopting SW-PBIS is slower compared to elementary schools. High schools represent approximately 34% of all schools in the US, but only 7% of those implement SW-PBIS. Out of all schools implementing SW-PBIS, only 13% of those are high schools. Recent research suggests that the latency between initial training and reaching adequate SW-PBIS implementing fidelity is longer on average for high schools, compared to both elementary and middle schools. To increase the number of high schools adopting SW-PBIS and implementing to fidelity, more attention is needed to identifying specific implementation components that are likely to be challenging for high school staff to implement. Therefore, the purpose of this brief is to summarize patterns in SW-PBIS implementation fidelity in 996 high schools across 31 U.S. states. The authors specially aimed to evaluate how high schools are implementing the components of SW-PBIS, and identify implementation strengths and needs and examined the following research question: What are the patterns of Tier I SW-PBIS implementation for high schools at low fidelity, partial fidelity, and high fidelity?