This article is based on a qualitative longitudinal study of children's changing peer relationships through childhood, with particular emphasis on experiences of disabled children. Initial observation of face-to-face-encounters among children in school made us aware of social inclusion and exclusion mechanisms relating to informal interaction rules negotiated and practiced by children. Through qualitative longitudinal fieldwork, these rules were identified, and our understanding of them developed, as changing social structures during childhood. Children not able to identify the nuances, signs and symbols in these rules become marginalised. Intellectually impaired children struggle to grasp the nuances without support, and their challenges increase with age. As the young people reached teenage years, children with mobility difficulties were more successful in adapting to the ways interaction rules developed. Their practical problems relating to time and space decreased over the course of their childhood.