The phenomenon of aggression among school-age adolescents has been known for a very long time. It concerns behaviours which cause physical, psychical or / and emotional harm. Nowadays, the problem of aggression is very up-to-date, and at the same time, very difficult and complex. The size of the phenomenon of aggression in Poland has been increasing year by year. Everyday, its subsequent manifestations are reported by the media. The reports published in pedagogical literature and everyday press, as well as the social feeling, are the evidence of the growing character of the phenomenon of aggression.