Urban street gangs flourish in the urban centres of the Cape Verdean archipelago. Most of their members belong to the male, young and economically disadvantaged strata of society. While in public discourse youth gangs are often peremptorily blamed for most of the violence and criminality that take place in the country, the internal dynamics of gang life often go unnoticed. Based on fieldwork in the cities of Praia and Mindelo, the article discusses the mechanisms that make Cape Verdean adolescents and youths join urban gangs and stick to them, despite the state’s politics of securitization and repression. Within this context, the experience of imprisonment is related to gang members’ pre-prison biographies and the conceptualization of prison itself, reinforced during individual ‘careers’ of marginality.