Gangs are present in about 34% of all jurisdictions in the United States. Given elevations in violence and victimization associated with gang involvement, effective means are needed for measuring involvement among individual youth. This is especially the case among youth receiving services for problem behavior who might benefit from targeted treatments helping them reduce involvement in gangs. We assessed gang involvement among 421 youth referred by the justice system for intensive home- and community-based mental health treatment. Using self-report survey and therapist-recorded data, we identified 94 (22%) youth as gang involved. Risk factor measures provided support for our classification, driven primarily by self-reported indicators of gang involvement as opposed to therapist-recorded indicators.