The purpose of this epidemiological study of psychopathological disorders was to obtain prevalence data on 55 behavior symptoms as they occur in kindergarteners and first and second graders. The behavior symptoms are commonly found in child guidance clinic populations. The population rated in this study was the kindergarten and first and second graders in the Urbana School system, which included 926 boys and 827 girls. The children were rated by their teachers with the use of the Quay Peterson problem checklist. The universality of the population and the data is limited because Urbana is a university town and the per capita income, education level, and youth of the town is higher than usual. Analysis of the data indicated that: (1) prevalence of many of the psychopathological symptoms is quite high, (2) boys have higher rates of acting out or disruptive symptoms, while girls have slight excess of neurotic type symptoms, (3) there is a tendency for many symptoms to decrease at age 5 with a slight increase again at 8 years, (4) total number of symptoms per child is significantly higher in boys than in girls, and (5) there is little doubt that not only do boys have more symptoms than girls, but female teachers consider boys more trouble than girls. (MH)