Results indicated significant differences between the mean rank of the total score of the HCR-20 and two subscales--the historical subscale (H) and the risk management subscale (R). The findings revealed that adolescents who victimized strangers had more violent risk factors compared to those who victimized family and other known victims. More specifically, the results on the Historical subscale showed that two items were particularly important for distinguishing between the two groups of adolescent offenders: (1) young age at first violent incident; and (2) prior supervision failure. Substance abuse problems, early maladjustment, and personality disorder were also characteristics of adolescent offenders who victimized strangers. On the other hand, the major mental illness item of the HCR-20 indicated that adolescents who victimized family or others known to them exhibited signs of mental illness more frequently than adolescents who victimized strangers. The findings have important implications for treatment and prevention. For example, the family members of adolescents experiencing mental illness symptoms should be prepared for a violent eruption and work toward preventing any vulnerable situations. Participants were 108 adolescents who were admitted to the Adolescent program of Montreal’s Phillip-Pinel Institute between February 1998 and April 2003. All participants were assessed using the HCR-20 checklist. Data were analyzed using the Mann-Whitney test. Tables, notes, references