This article describes a collaborative faculty research project developed to support a university preschool in their transition to becoming an inclusive programme. The project, conducted in the southeastern region of the United States, facilitated the development and implementation of the first two tiers of a system of Program-Wide Positive Behavior Supports (PW-PBS) in the preschool. The primary investigators developed and provided 15 h of PW-PBS training for the preschool teachers and staff during the first half of the school year. During the second half of the school year, the teachers and staff implemented PW-PBS, and the investigators administered fidelity of implementation measures. The completed fidelity measures were used to provide feedback and follow-up support. Pre-post measures of the effects of PW-PBS on children's social skills and problem behaviours were also administered and the social validity of PW-PBS was evaluated. Results indicate that after being trained on tiers one and two in the first half of the school year, teachers were able to implement PW-PBS at 51% fidelity in January. After one follow-up session with the investigators in March, fidelity increased to 58%. Pretest-posttest measures showed significant increases in social skills and significant decreases in problem behaviours among child participants. Finally, the results indicate the adult participants found PW-PBS to be a socially acceptable intervention. Implications and future directions are discussed.