This article reviews recent literature on the effects of integrating children with severe learning difficulties (or severe intellectual disabilities) into mainstream schools. It begins with a brief discussion of some of the inherent methodological problems in evaluating integration. This is followed by a review of the literature in the following areas: the role of support workers in facilitating integration; the effect of integration on communication and linguistic interaction; the relevance of curriculum differentiation; the impact of the age, ability and behaviour of the children with disabilities on integration; the effects of integration on children without disabilities; the attitudes of mainstream teachers and Local Education Authority staff towards integration. It concludes with a summary of the main findings and discusses the implications for future policy, provision and research.