Bully/victim problems among school children are a matter of considerable concern in Scandinavia and, more recently, in a number of other countries as well. Estimates based on the author's large-scale surveys indicate that some 9% ofthe students in grades 1 through 9 are fairly regular victims ofbullying and that 6-7% engage in bullying others with some regularity. It is argued that it is a fundamental democratic right for a child to be spared the oppression and repeated humiliation implied in bullying. The author has developed a school-based intervention programme against bullying, the effects of which were evaluated in 42 schools over a period of two years. Analyses indicate that the frequency of bully/victim problems decreased by 50-70%. In addition, the prevalence of antisocial behaviours in general such as vandalism, theft, drunkenness and truancy showed a substantial drop. The main content ofthe "core" programme as well as its key principles are presented. The overriding goal ofthe programme can be described as a "restructuring ofthe social environment". The programme emphasizes behaviours and attitudes characterized by a combination ofpositive involvement from teachers and parents, firm limits to unacceptable behaviour ("we don t accept bullying in our class/school"), and consistent use of non-hostile non-corporal sanctions on rule violations. Explanations ofthe positive results include changes in the opportunity and reward "structures" for bullying behaviour.