The peacebuilding literature has long emphasised that youth involvement is key to ensuring long-term peace. In the aftermath of the 'no' victory in the Colombian peace plebiscite, great emphasis has been placed on youth movements' push for peace. However, statistics on violent groups in Latin America show that these groups are largely made of young people. The position of young people at the crux between peacebuilding and perpetuation of violence needs to be contextually unpacked. While studies have tended to focus on youth movements, the question of how non-organised, (self-)marginalised youths relate to peacebuilding is largely unaddressed. Based on 9 months of ethnographic fieldwork with outcast adolescents in the conflict-affected town of San Carlos and marginal neighbourhoods in the close-by city Medellín, this paper addresses this gap.