The article synthesises data from two ethnographic projects, which both explore interactions of children in age-mixed groups in primary schools. It illuminates critical perspectives on social orders and children's interactions in age-mixed classes by showing how pupils in age-mixed groups become involved in power relations and how the teacher's authority and institutional rules are intricately interwoven into the social orders of the peer culture. The article highlights children's complicity with the teacher and her expectations and accordingly questions the notion of an increase of children's autonomy in age-mixed groups.