The proposed study will be a 6-week open label study evaluating aripiprazole in the treatment of 12 male post-pubertal adolescents (13-17 years, Tanner Stage 4) diagnosed with conduct disorder. The initial dose depending on the weight of the patient will be as follows: < 25 kg = 1 mg/d; 25-50 kg = 2 mg/d; 50-70 kg = 5 mg/d; > 70 kg = 10 mg/d (Data on File, 2003, Bristol-Myers Squibb). For the first two weeks of the study, the dose will be flexible based on response and tolerance and thereafter will remain fixed.