The current study examined differences between gang-involved and non-gang-involved homeless African American male youth with regard to negative affect, substance use, and antisocial/violent behavior. A total of 69 homeless African American young men were recruited from community agencies and completed structured face-to-face interviews. Overall, gang members reported higher rates of negative mental and physical health outcomes than did non-gang members, with current gang members reporting higher levels of depression and anxiety, greater levels of antisocial and violent behavior, and higher levels of lifetime alcohol and marijuana use. Multiple linear regression analyses revealed that greater levels of gang involvement were associated with more frequent lifetime use of alcohol and marijuana and higher levels of participation in violent behaviors. Implications of these findings for interventions with homeless African American male youth and future research directions are discussed.