The aim of this study was to evaluate the mediating role of the justification of violence schema in the relationship between exposure to violence and reactive and proactive aggressive behavior. We differentiated between direct and indirect exposure in four contexts: home, neighborhood, school and TV. A total of 675 children, aged between 8 and 12 years, participated in the study. They answered questionnaires about exposure to violence, justification of violence, and proactive and reactive aggressive behavior in two waves six months apart. The results showed that witnessing violence at home and on TV predicted aggressive behavior, and this relationship was mediated by the justification of violence. Victimization in all contexts predicted aggressive behavior and this relationship was generally mediated by the justification of violence.