The purpose of the study was to conduct a randomized controlled trial (RCT) to demonstrate efficacy of the Class-wide Function-Related Intervention Teams (CW-FIT) program. The study was designed to replicate an initial RCT conducted by the CW-FIT developers in 1 site, with 2 additional research groups not involved in its development. The study was conducted across 3 states, in 21 culturally diverse schools, and with 83 teachers (classrooms) assigned to CW-FIT and 74 teachers (classrooms) assigned to the comparison group. The CW-FIT intervention included teaching prosocial skills and use of differential attention (teacher praise and points) for appropriate behaviors using a group contingency, class teams, goal setting, points, and rewards. Class-wide student on-task behavior improved, teacher praise and attention to appropriate behaviors increased, and reprimands decreased in the CW-FIT classes with significantly fewer changes over time for the comparison group.