This article explores the development of effective ways of preventing violence in the school environment, through on-site research, as well as the authors’ experience in the field of initial and continuing teacher training. First, we present some observations about the prevalence of violent behaviour in Québec schools. These results are accompanied by reflections on different ways of analysing the "school effect". Then we present the principles on which the most effective violence prevention approaches have been based. Finally, we examine the challenges faced both by practitioners and researchers in developing and establishing prevention measures or programs in the school setting.