Because youth gangs tend to cluster in disadvantaged neighborhoods, adolescents living in such neighborhoods are more likely to encounter opportunities to join youth gangs. However, in the face of these opportunities, not all adolescents respond in the same manner. Those with preexisting psychopathic tendencies might be especially likely to join. In this study, we tested whether a combination of individual propensity and facilitating neighborhood conditions amplifies the probabilities of youth gang affiliation. A subset of 3,522 adolescents was selected from a nationally representative, prospective sample of Canadian youth. Psychopathic tendencies (i.e., a combination of high hyperactivity, low anxiety, and low prosociality as compared to national norms) were assessed through parent reports, while neighborhood characteristics (i.e., concentrated economic disadvantage and residential instability) were derived from the 2001 Census of Canada. Our results indicated that neighborhood residential instability, but not neighborhood concentrated economic disadvantage, interacted with individual propensity to predict youth gang membership. Adolescents with preexisting psychopathic tendencies appeared especially vulnerable mainly if they were raised in residentially unstable neighborhoods.