Bullying is described as aggressive behavior normally characterized by repetition and imbalance of power. It may be considered as a normative in many group settings, but socially unacceptable within the ethos of a democratic society. The history of research and intervention on bullying in schools during the past two decades is summarized. School bullying emerges as an international issue, and we have increasing knowledge of its nature and effects. There is also growing experience of the effectiveness of a range of school-based intervention strategies. These issues are discussed in relation to the 10 articles from 9 countries that constitute the remainder of this Special Issue on Bullying in Schools. Aggr. Behav. 26:1–9, 2000. © 2000 Wiley-Liss, Inc.