To identify the prevalence of ADHD symptoms among non-referred children, parents' ratings based on DSM-III-R criteria for ADHD were obtained for 1022 metropolitan children of ages 4 to 12. The prevalence rates of fourteen behavior items were markedly lower for boys of ages 10-12 than of ages 7-9, and for girls of ages 7-9 than of ages 4-6. 41.5% of the 7.7% subjects meeting ADHD criteria had been identified by their teachers as having problems symptomatic of ADHD, and one third had been reported by their parents as having conduct problems and emotional difficulties. A factor analysis revealed three factors: inattention; hyperactivity; and excessive verbal activities.