This report presents data from the Ontario Child Health Study on the prevalence of individual emotional symptoms, the variation of prevalence rates of emotional disorders as a function of demographic factors, and the rates of service utilization for children with these disorders. To survey Ontario children from 4 to 16 years of age, a stratified random sample of 3,294 children was drawn from all household dwellings listed in the 1981 Census. The prevalence rates for emotional disorders in male and female children aged 4 to 11 years were 10.1% and 10.7%, respectively. For adolescents aged 12 to 16 years, the prevalence rate rose to 13.7% for females and fell to 5.0% for males. Children with emotional disorders were frequently found to meet criteria for more than one disorder. Only one in five children with emotional disorders had received mental health or social services in the 6 months prior to the survey.