The developmental cascade that leads to poor school performance may originate in children's susceptibility to mental health problems that trigger suboptimal social experiences, such as bullying victimization, in the school context. Therefore, this research project will examine a) the genetic etiology of bullying victimization from a developmental perspective (WP1), b) whether genetic predispositions for mental health problems can explain lower levels of academic achievement via higher levels of bullying victimization (WP2) and c) whether an antibullying program can moderate the heritability of bullying victimization (WP3). This research will inform us on how genes contribute to the development of bullying victimization and the success, failure, and mechanisms of antibullying intervention strategies. Based on the results, preventive and indicated actions could be developed and tailored to the needs of children who are at higher risks of being bullied.