In the public school system, administrators and educators have multi-faceted responsibilities, including educating students, providing a safe environment, and ensuring a positive school climate conducive to student learning. Positive Behavior Interventions and Supports (PBIS) is a model many schools have adopted to assist in behavior modification to increase positive school climate and as an alternative to adverse discipline. The purpose of this program evaluation is to ascertain the impact of implementation on office referrals and school climate. PBIS consists of core components that address environmental situations, employ explicit teaching expectations, and use incentives to promote desired behaviors. This mix-methods program evaluation utilized quantitative and qualitative approaches. Thirty-two certificated staff members and six classified staff members at one school participated in a Perception Survey on PBIS implementation and its effects on school climate. Members of the PBIS team also participated in a Tiered Fidelity Inventory survey to inform on the progress of implementation fidelity. Results from the first year of implementation confirmed that the school is making progress towards program fidelity but is not yet there. Findings from the Perception Survey indicated that participants who perceived a positive change in school climate attributed it to PBIS implementation. Participants also reported a decrease in office referrals, although quantitative data in this area are inconclusive due to school closures brought on by COVID-19. The gap in data warrants additional considerations and suggestions for future school leaders. Further longitudinal evaluation is still needed to fully ascertain the impact of PBIS implementation on school climate. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]