This study investigated the influence of student-teacher relationships and attitudes toward bullying on middle school students' bullying behaviors. Gender and grade differences were also examined. Data were collected from 435 middle school students. Results indicated that students' attitudes toward bullying mediated the relationship between student-teacher relationships and physical and verbal/relational bullying. There was a significant group difference on student-teacher relationships and attitudes toward bullying between bully, bully-victim, victim, and bystander groups and students not involved in bullying. In addition, sixth graders reported significantly more positive student-teacher relationships than seventh and eighth graders. Implications for the role of both cognitive and behavioral bullying intervention and prevention efforts are discussed.