Background: Restricted and repetitive behaviours and interests are one of the two core diagnostic features of autism. Frequent, severe restricted and repetitive behaviours and interests can cause significant difficulties for individuals with autism. These behaviours can impede participation in activities at home and in the community and affect social interaction. To date, there is little research into the effects of restricted and repetitive behaviours and interests in the school environment. This study aimed to document the effects of restricted and repetitive behaviours on participation for children with autism. Method and Results: The data used in this study has been collected through the Cooperative Research Centre for Living with Autism’s (Autism CRC) Longitudinal Study of Australian children with Autism (LASA). Caregivers of children on the spectrum aged 9–10 years (n = 131) completed the Participation and Environment Measure for Children and Youth school section and the Developmental Behavioural Checklist- Parent Version. Caregivers reported on frequency of child's participation and level of involvement in school activities and the amount and frequency of restricted and repetitive behaviours. Analysis was performed using a series of Mann-Whitney U tests at PEM-CY item‐level which revealed that children with elevated lower order restricted and repetitive behaviours participate less in getting together with peers outside of class. Conclusion: Lower order restricted and repetitive behaviours affect participation in socialising with peers. This is concerning as limited or absent peer relationships can negatively influence health and mental health. Further investigation is warranted through multi informant designs that seek the perspectives of the child and education specialists.