The study, part of a larger evaluation of a multimedia violence prevention study, examined stability and change of bullying over a 4-month interval in 516 middle-school students in grades 6-8. There was a significant increase in bullying behavior from Time 1 to Time 2 for 6th-grade students; no significant change in bullying was found among 7th- or 8th-graders. For 6th-graders, a greater confidence in using non-violent strategies was associated with less bullying at Time 2, while beliefs supportive of violence and misconduct, less positive adult influences, and more negative peer influences were associated with greater likelihood of bullying at Time 2. Higher levels of impulsivity, anger, and depression were also associated with greater levels of bullying over time. The study found that messages conveyed to students by teachers and other significant adults in the community appeared to have an important impact on students' behavior. In addition, the significance of beliefs supporting violence and confidence in using nonviolent strategies on future bullying behavior suggested a role for teaching and practicing prosocial skills. However, the article suggested that research was needed to explore how this instruction could be coupled with other prevention strategies such as changing the school environment or providing teacher and parent training to reduce bullying behavior. Figures, table, references