This paper focuses on the impact of peer mediation as a strategy for promoting social inclusion in primary school settings. Peer mediation constituted one of the interventions in the UK Government-sponsored On Track programme and evaluative data from this project are reported. The paper reports on trends in bullying and anti-social behaviour in nine schools where peer mediation was deployed. Quantitative results from "My life in School" checklists and a questionnaire measuring teacher perceptions are reported. Qualitative evidence is also reported from focus groups undertaken with pupils. The benefits of mainstreaming and further dissemination of the approach are discussed. (Contains 2 tables.)