The article investigates how exposure to gang-affiliated peers affect youth’s social behaviors and attitudes. Much of the literature finds that exposure to gangs contributes to youth’s antisocial outcomes. According to other studies, however, it can also promote prosocial behaviors. The present article reexamines this contradictory evidence, exploring potential complementarity of both reactions to gangs. Using survey of 1,944 youths from rural Colombia, I compare adolescents who are and are not in the school class with members of youth gangs. I exploit the fact that schools in rural Colombia are unsegregated. Moreover, the presence of youth gangs across these schools is linked to prior incidence of armed conflict rather than typical forms of social disadvantage. Exposure to gang-affiliated classmate can thus be considered as a quasi-random shock to affected youth. The analysis reveals gender differences in the effect of youth gang exposure. I find that girls react to male gang classmate by increased involvement in prosocial organizations. Boys, by contrast, adjust to male gangs by expressing more antisocial attitudes. The article shows that the well-documented antisocial adjustments to gangs are—population-wide—complemented by prosocial reactions, with gender being a key moderator. I discuss implications of these findings for theories of violence, gender, and neighborhood effects. I also provide suggestive evidence that my findings are applicable to the US context.