This study reports a short-term prospective investigation of the role of peer groupvictimization in the development of children's behavior problems, at home and in school.Sociometric interviews were utilized to assess aggression, victimization by peers, and peerrejection, for 330 children who were in either the third or fourth grade (approximate mean agesof 8–9 years old). Behavior problems were assessed using standardized behaviorchecklists completed by mothers and teachers. A follow-up assessment of behavior problems wascompleted 2 years later, when the children were in either the fifth or sixth grade (approximatemean ages of 10–11 years old). Victimization was both concurrently and prospectivelyassociated with externalizing, attention dysregulation, and immature/dependent behavior.Victimization also predicted increases in these difficulties over time, and incremented theprediction in later behavior problems associated with peer rejection and aggression. The resultsof this investigation demonstrate that victimization in the peer group is an important predictor oflater behavioral maladjustment.