A total of 23 boys met DICA-P manic symptom and clustering criteria in a diagnostic investigation of 233 outpatient boys between ages 6 and 10. In this manic-symptom group, the most frequently endorsed of an average of five manic symptoms were extreme mood changes, difficulty concentrating, feeling too `up' to sit still, and racing thoughts. Comparison groups were 23 non-manic boys seen next in the investigation and 23 non-manic boys matched to the manic-symptom boys on symptoms of three comorbid disruptive disorders (ADHD, ODD and CD). Manic-symptom boys differed significantly from next-seen boys, but not from matched comorbid boys, in number of oppositional symptoms and pervasiveness of problems. Manic-symptom boys differed significantly from next-seen boys on six of eight mother-rated RCBCL factors. In contrast, manic-symptom and matched comorbid boys did not differ on any of eight RCBCL factors, which suggests that the RCBCL differences can be attributed to shared ADHD, ODD and/or CD. However, manic-symptom and matched comorbid boys tended to differ on RCBCL Anxiety/Depression. On the teacher-rated TRF, manic-symptom boys were rated higher than next-seen boys on four internalizing factors, and higher than matched comorbid boys on two of those factors, including Anxiety/Depression. Thus, manic symptomatology also predicted substantial emotionality, which was not a controlled comorbidity. The findings of this and other studies suggest that there is a mania dimension or syndrome, which may be an indicator of true bipolar disorder-or simply a marker for disruptive comorbidity, behavioral and emotional multimorbidity, or general severity of psychopathology.