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. The country’s dominant discourse around “stable and lasting peace” starkly contrasts with these youths’ conceptions of peace and violence. Their daily experiences of interpersonal physical and symbolic violence within their families and communities lead them to continue seeing violence as a legitimate mean of interaction. Feeling rejected by the rest of society, they reject any form of civic engagement in turn. Rather, they opt for moving from the town to the city and getting involved in the micro-traffic business and joining urban gangs, contributing to perpetuating some of Colombia’s most pressing threats to peace. Rather than simplistically framing engagement in violence as an inherent tendency of Latino masculinities, the aim is to understand these young people in their own terms, exploring how social marginalisation relates to engagement in violence. Giving voice to the narratives of these ‘other’ youths, that are not captured by the dominant media discourse, this paper contributes to broader debates intersectional identities and exclusionary dynamics in post-conflict societies, aiming to bright theoretical and policy-relevant insights to peacebuilding in Colombia.