Research has demonstrated a link between internalizing factors and bullying perpetration and peer victimization; however, few studies have examined predictors of cognitive and psychosocial factors, such as locus of control and hopelessness. The current study examined cognitive and psychosocial factors in bullying perpetration and peer victimization in a sample of 469 middle school students. A mediator model of hopelessness was also investigated. Students involved in bullying reported a greater external locus of control compared with peers who were not involved in bullying. Bully-victims endorsed the highest externality. Results showed that hopelessness fully mediated the relationship between verbal/relational victimization and external locus of control for the victim group, but not the bully-victim group. Implications for bullying prevention and intervention efforts are discussed.