The control group of n=70 children will receive in the first treatment phase (pre- to post1-assessment) an alternative child-focused intervention with a supportive Treatment Programm including techniques to activate resources of the child (Supportive Therapie zur Aktivierung von Ressourcen bei Kindern, STARK) with 16 weekly sessions. In the second treatment phase (post1- to post2- assessment) those children with sustained severe peer related aggressive behavior receive 16 weekly child-focused sessions with the treatment modules of ScouT . Those children with no severe peer related aggressive behavior receive 2 booster sessions of STARK within a 16 week period.