Consistent with prior studies, this study found that the level of psychopathic features as measured by the Psychopathic Checklist: Youth Version (PCL:YV) predicted the level of institutional maladjustment, historical behavioral problems, and aggression before treatment. The study found that youths with psychopathic features showed a significant response to treatment. In addition, those who responded to treatment were significantly less apt to reoffend violently. Response to treatment in the form of improved treatment compliance and reduced aggression was significantly predicted by the length of time in treatment. The results suggest that treatment of youths with psychopathic features will need to be of relatively high intensity and long duration. Prior studies of the treatment response and institutional behavior of adolescents with pronounced psychopathic features have revealed several consistent findings: (1) juveniles with more psychopathic features tend to be more disruptive and aggressive in institutions and treatment programs; (2) are more apt to drop out; and (3) make less progress in treatment. This study examined the relation between psychopathic features and treatment programs in a group of 86 delinquent boys who were consecutively admitted to the Mendota Juvenile Treatment Center (MJTC) in 1999 and 2000. Tables and references