One study involved a representative sample of 1,163 seventh-grade and eighth-grade students attending secondary schools in the German cities of Erlangen and Nuremberg. Questionnaires were used to assess experiences of violence at school from the perspectives of the offender and the victim, delinquent behavior, and other behavioral problems. Information was solicited on family of origin, personality, social competence, coping behavior, academic performance, school climate, integration into peer groups, activities in peer groups, mass media use, and leisure-time behavior. Processes of social information processing were operationalized with conflict scenarios. The study found high correlations between school bullying and delinquent and general antisocial behavior, particularly the commission of property offenses, acts of violence, drug offenses, noncriminal aggression, truancy, intensive substance use, and risk-taking in driving. Coming from a lower class family with structural problems was related to a slight increase in the risk of aggression and delinquency; however, relations to perceived child-rearing behavior and family interaction climate were much stronger predictors of aggression and delinquency. Aggressive and delinquent adolescents were more impulsive, less socially competent, and more dominant than others. They also had more attention deficits and identity problems. Victims of aggression also had attention deficits and identity problems, showed more avoidant coping, were less popular, and somewhat less socially competent. In the second study, the variable-oriented analysis was extended with a person-related or typological analysis. Self-reports and teacher ratings were used to identify five subgroups of adolescents: ones who behaved particularly aggressively without being victims themselves (bullies); ones who were victimized particularly frequently without being aggressive themselves (victims); ones who were both very aggressive and frequently victimized (bullies/victims); ones who were not particularly either one or the other (normals); and adolescents with particularly high social competence (social competents). Analyses of variance revealed significant differences between these five subgroups in almost all risk domains. Bullies exhibited risks in a particularly large number of domains; and as a group they were strongly underrepresented among those with the least risk. Both studies revealed that aggressive behavior at school is only one aspect of a broader delinquency and antisocial behavior. Guiding principles for prevention derived from the findings include early problem diagnosis, a multimodal approach to various risks, realistic expectations of success for measures in single domains, and a focus on the methodologies of social information processing. 41 tables, 34 figures, 477 references, and a subject index