Objective: To build on prior research documenting the impact of School-wide Positive Behavioral Interventions and Supports (SWPBIS) on school climate and discipline problems to examine the extent to which it affects bullying and peer rejection during the transition into early adolescence.

Design: Three-level models were fit using hierarchical linear modeling to determine the effect of SWPBIS on children's involvement in bullying.

Setting: Thirty-seven Maryland public elementary schools.

Participants: Data involved 12 344 children (52.9% male, 45.1% African American, 46.1% white) followed up longitudinally across 4 school years.

Intervention: A randomized controlled effectiveness trial of SWPBIS.

Outcome measures: Reports from teachers on bully-related behaviors were assessed through the Teacher Observation of Classroom Adaptation-Checklist.

Results: Analyses indicated that children in schools that implemented SWPBIS displayed lower rates of teacher-reported bullying and peer rejection than those in schools without SWPBIS. A significant interaction also emerged between grade level of first exposure to SWPBIS and intervention status, suggesting that the effects of SWPBIS on rejection were strongest among children who were first exposed to SWPBIS at a younger age.

Conclusions: The results indicated that SWPBIS has a significant effect on teachers' reports of children's involvement in bullying as victims and perpetrators. The findings were considered in light of other outcomes for students, staff, and the school environment, and they suggest that SWPBIS may help address the increasing national concerns related to school bullying by improving school climate.