This qualitative research explored 9- to 12-year-old children's citizenship participation at primary school in the Republic of Ireland. During 2016-2017, 160 children from 6 co-educational primary schools participated. Through a process of grounded analysis, children are identified as active "citizen-peers" of their peer groups. As "citizen-peers," children used social strategies to assert their agency and autonomy within the adult-controlled school environment. Social bonding between children also influenced the ways "citizen-peers" negotiated peer group social hierarchies. Inductive analysis of observational data identifies children's social strategies as covert and overt forms of "Collective Social Action" ("CSA"); motivated by competition and/or protest against the activities children did not want to participate in at school. This research found that low social bonding between children affects peer solidarity, which suggests that social bonding is an important aspect of children's collaboration as "citizen-peers" at school.