This article discusses children's responsibility in care practices from a relational perspective. The aim is to understand how responsible action takes place and is experienced in the lives of children who reside in a community in the city of Rio de Janeiro, Brazil. We interrogate the universalist sense of the notion of responsibility regarded as a juridical duty to be met in order that children's citizenship can be validated. An ethnographic research project with children from 4 to 12 years of age was carried out over a period of 5 months. The results show that children's actions address moral issues referring back on what they judge to be valuable to secure in relevant relationships rather than on learnt prescribed rules of behavior. The analysis points to the importance of foregrounding the affective and relation dimension of children's citizenship illustrated here as caring practices in processes of interdependence.