Bullying in schools is now regarded as an important social problem which schools need to address. However, recent evaluations of existing anti-bullying programs have not indicated a high level of success in the reduction of bullying. This article seeks to critically examine the theoretical perspectives that have been adopted in explaining the prevalence of bullying and their implications for the work of schools. Five different theoretical perspectives are identified and examined. Each is shown to have some empirical support and to have influenced the thinking adopted by schools and actions undertaken in addressing bullying. However, none can claim to provide a complete explanation for bullying behaviour in schools, nor form the basis for a comprehensive approach to the problem. It is suggested that educators recognize both the strengths and limitations of existing theoretical perspectives.