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. (C) 1998 Elsevier Science BN. All rights reserved.