Children have an unsettled relationship with the status of citizenship, being given some rights, responsibilities and opportunities for participation, and being denied others. Yet if citizenship is conceived of as a practice, children can be firmly seen as citizens in the sense that they are social actors, negotiating and contributing to relationships of social interdependence. This article develops understandings of children’s agency in citizenship and some of the different ways in which children’s actions enact them as interdependent citizens. It presents one aspect of the understanding of citizenship generated from research with six groups of marginalized children, aged 5–13, in Wales and France. Synthesizing the research groups’ descriptions of activities they associated with the component parts of citizenship with citizenship theory, these children can be seen to engage in actions of citizenship that include making rules of social existence, furthering social good and exercising freedoms to achieve their own rights. Their activities also transgress the boundaries of existing balances of rights, responsibilities and statuses, through their (mis)behaviour, in ways that can be interpreted as Acts of citizenship. In children’s everyday activities, however, the distinction between actions and Acts of citizenship can at times be blurred. This is because recognizing aspects of children’s practices as citizenship is a challenge to dominant definitions of citizenship, and claims a new status for children. Exploring children’s citizenship in these ways has the potential to widen understandings of participation and appreciation of broader aspects of children’s agency in citizenship.