Educators can employ a variety of classroom management strategies in their efforts to foster a classroom environment in which all students can learn. "Class-Wide Function-Related Intervention Teams (CW-FIT)" is one such strategy. As part of "CW-FIT," teachers establish classroom rules, provide instruction on target skills, place students into teams, and then reward teams for demonstrating target skills, all with the aim of improving student behavior and creating a positive learning environment. "CW-FIT" seeks to reinforce appropriate behaviors, minimize social attention to inappropriate behaviors, and provide self-management tools to individual students who need extra support. The What Works Clearinghouse (WWC) reviews existing research on educational interventions to identify evidence-based programs and practices. This WWC intervention report summarizes the available evidence on the effects of "CW-FIT" on student and teacher outcomes. Eight studies of "CW-FIT" meet WWC standards and contribute to the effectiveness ratings in this report. Based on the eight studies, there is strong evidence that "CW-FIT" positively impacted student behavior and promising evidence that "CW-FIT" positively impacted teacher practice. [For the Intervention Brief, see ED628224. For the Single-Case Design Appendix, see ED628225.]