The current study investigated bullying behaviors in 284 school children in the fourth through seventh grades at the time of the initial assessment. Peer ratings of bullying behavior were obtained at the end of the spring semester of one school year and at the end of the fall semester of the next school year. Importantly, peer ratings were obtained by assessing not only the level at which participants actually bully other students but also whether participants help bullies to hurt the victim (assister), encourage bullies (reinforce), or help the victim of bullying (defender). Our results did not support the utility of differentiating between bullies, assisters, or reinforcers. Specifically, these bullying roles were highly intercorrelated, both concurrently and across school years, and they showed similar correlations with aggression and several characteristics often associated with aggression (i.e., conduct problems, callous-unemotional traits, and positive expectancies about aggression). In contrast, ratings of defending designated a particularly prosocial group of students. Finally, whereas bullying appeared to be very similar in boys and girls, it was somewhat more stable across school years and was related to lower levels of prosocial behavior in boys, both of which could suggest that bullying may be somewhat more related to social group dynamics in girls. Copyright © 2011 John Wiley & Sons, Ltd.