This study examines sociodemographic characteristics and social-environmental factors associated with bullying during the elementary to middle school transition from a sample of 5th-grade students (n = 300) in 3 elementary schools at Time 1. Of these, 237 participated at Time 2 as 6th-grade students. Using cluster analyses, we found groups of students who reported no increase in bullying, some decrease in bullying, and some increase in bullying. Students who reported increases in bullying also reported decreases in school belongingness and teacher affiliation and increases in teacher dissatisfaction. Students who reported decreases in bullying also reported decreases in victimization. These findings suggest that changes across the transition in students' relations to school and their teachers are predictive of changes in bullying.