Bullying is a significant public health concern associated with mental health risks. Negative bullying outcomes extend beyond targets, with students who witness bullying reporting negative associated mental health consequences. Because bullying often occurs within the school setting, understanding the relationship between witnessing bullying and internalizing symptoms within the school environment can help shape school-based bullying prevention. The purpose of this study was to examine sense of school belonging as a mediator of the relationship between witnessing bullying and internalizing symptoms. We conducted two studies with middle school students ( = 130; = 147) in which we used structural equation modeling (SEM) to test the mediational model. Results from Study 1 and Study 2 supported the mediational model, indicating that one explanation for the relationship between witnessing bullying and internalizing symptoms is that witnessing bullying negatively impacts students' sense of school belonging, which in turn increases internalizing symptoms. Results from this study provide support for the importance of students' perceptions of school climate in the development of internalizing symptoms related to witnessing bullying. Implications for school-based bullying prevention programs are discussed.
