This White House report investigates the essential role that peers play in promoting or preventing bullying. Bullies use bullying to attain success and recognition; their success in doing so depends on the characteristics of the bully, the relationship that exists between bullies and those whom they target for harassment, and the reactions of classmates who witness bullying. The author describes the two social worlds of bullying: Marginalized bullies may resort to bullying from an inability to control their impulsive actions or from a desire to gain status, whereas connected bullies may use their popularity to dominate low-status peers. Bullies and victims often have a previously existing relationship that presages bullying before it happens, which, if known, would alert knowledgeable adults about possible trouble spots. Educators who exclusively target peripheral, antisocial cliques as the engine of school violence problems may leave intact other groups that are more responsible for mainstream peer support of bullying. A strong step educators could take would be to periodically ask students about bullying and their social relationships. (Contains 2 endnotes.)