Most previous research work on antisocial conduct disorders in children has not separated children with hyperkinesis caused by dysfunction of the brain from those whose hyperkinesis stems from psychosocial problems. Using an entirely fresh approach, this work develops methods to assess hyperactivity and other behavioral problems, and to measure disturbance of attention and neurological development. The study described in this monograph applies these methods in an epidemiological setting. It clearly identifies and compares children with hyperactivity, conduct disorder, and both problems together, with a control group of normal children.