EN
The intensifying phenomenons of aggression among school children induce to undertake research on this phenomenon. The authoress presents an overview of research publications dealing with factors determining aggressive behaviours in home, school and in the peer environment. During the research on teachers and school children, carried out in 2002 at two 'gymnasiums' in Chorzów she gathered the data on the factors determining aggressive behaviours of gymnasium teenagers. They are connected with school environment (mainly unfavourable 'atmosphere' at school, too much children in the classes), home environment and the way of spending spare time by the school children (mainly as members of informal groups of peers). She also formulates some practical conclusions enabling to promote effective prevention which should become a social priority. Knowledge of conditions of this phenomenon