Countries emerging from armed conflict often experience heightened violence and youth gang activity. Following the signing of peace accords with the Revolutionary Armed Forces of Colombia-People's Army (FARC-EP), what are Colombia's risks in terms of youth gangs? To assess these risks, this article draws from gang research and literature on postwar violence to identify six factors that recur in postwar environments and are likely to fuel a rise in gangs: illicit economies and criminal networks, exposure to violence, marginalization, social disorganization, security gaps and state responses, and former combatants. After analyzing Colombia's risks with reference to each of these, the article concludes that the strengthening ties between youth gangs and Colombia's illicit economies, mediated by adult-run criminal networks, increase gang numbers and violence. Moreover, some disadvantaged, urban neighborhoods are vulnerable to gang escalation due to the effects on local youths of protracted violent exposure, marginalization, and social disorganization. Finally, while ex-combatant recidivism and security gaps are prominent concerns in Colombia, they are not expected to contribute significantly to youth gang dynamics in urban areas.