The article explores child participation from the perspective of the sociology of action. Despite the important literature on child participation following adoption of the UNCRC, a consistent theory of child participation is still missing. The distinction between the child as a subject of rights and the child as a social actor draws attention to the cumulative and systemic nature of action. Applications of a new model going in this direction are presented. They foster discussion on children’s agency and give insights for assessing implicit theories of action lying behind child participation.