Objective: This study examined the influence of hurricane impact as well as family and individual risk factors on posttraumatic stress (PTS) symptoms and substance involvement among clinically referred adolescents affected by Hurricane Katrina. Method: A total of 80 adolescents (87% male; 13-17 years old; mean age = 15.6 years; 38% minorities) and their parents were interviewed at the adolescent's intake into substance abuse treatment, 16 to 46 months postdisaster. Independent measures included hurricane impact variables (initial loss/disruption and perceived life threat); demographic and predisaster variables (family income, gender, predisaster adolescent substance use, predisaster trauma exposure, and parental substance abuse); postdisaster family factors (parental psychopathology, family cohesion, and parental monitoring); and postdisaster adolescent delinquency. Results: Hierarchical multivariate regression analyses showed that adolescent substance involvement was associated with higher family income, lower parental monitoring (adolescent report), and more adolescent delinquency. Adolescent-reported PTS symptoms were associated with greater hurricane-related initial loss/disruption, lower family cohesion (adolescent report), and more adolescent delinquency, whereas parent-reported adolescent PTS symptoms were associated with greater parental psychopathology, lower parental monitoring (adolescent report), and lower family cohesion (parent report). Conclusions: The results suggest that hurricane impact was related only to adolescent-reported PTS. However, certain postdisaster family and individual risk factors (low family cohesion and parental monitoring, more adolescent delinquency) were associated both with adolescent substance involvement and with PTS symptoms. Identification of these factors suggests directions for future research as well as potential target areas for screening and intervention with substance-abusing adolescents after disasters. (Contains 4 tables.)