Schoolwide positive behavior interventions and supports (SWPBIS) is currently implemented in more than 23,000 schools nationally and internationally. Several reviews have examined the SWPBIS evidence base, including a meta-analysis of single-case design research. However, to date, there has not been a review of group-based experimental research (e.g., randomized controlled trials [RCTs]) on the school-level effects of SWPBIS implementation to reduce disciplinary exclusion, including office discipline referrals and suspensions. Therefore, we conducted a systematic review and meta-analysis following What Works Clearinghouse procedures to investigate that relationship. We identified four group experimental studies that included disciplinary exclusion as an outcome variable; two RCTs and two quasi-experimental designs. Overall, 90 schools, including both elementary and high schools, were evaluated. A statistically significant large treatment effect (g = -.86) was found for school suspension, but no treatment effect was found for office discipline referrals. Implications for future research are discussed.