The past decade has seen an increase in the number of students with autism attending mainstream educational provision. Improving outcomes for this group is a complex issue given the deficit of evidence-based practice. A new peer mentoring programme developed for students with autism in mainstream secondary schools was evaluated using a combination of quantitative and qualitative measures. Twelve students with autism and 36 students without autism participated in the programme across five schools in the south-east of England. Students with autism were assessed using the Harter Self-Esteem Questionnaire, Loneliness and Social Dissatisfaction Scale and the Anti-Bullying Alliance survey. Semi-structured interviews were conducted to record their views and experiences of the programme. Significant gains in self-esteem, social satisfaction and a reduction in bullying were seen over the course of the programme. These findings have wider implications for the ways in which educational approaches, strategies and interventions are developed and delivered in schools.