Quinn, Robert W. (Department of Preventive Medicine and Public Health, Vanderbilt University School of Medicine, Nashville, Tennessee 37232), and C. F. Federspiel. The occurrence of hemolytic streptococci in school children in Nashville, Tennessee, 1961–1967. Am J Epidemiol 97: 22–33, 1973.—The purposes of this research were to determine the natural occurrence of hemolytic streptococcus in the throats of children during their first 6 years of school and to determine some of the epidemiologic factors influencing incidence. From 434 children, 22,627 cultures were obtained; 101 children were followed the entire 6 years. Hemolytic streptococci were isolated from 18% of all cultures; 11.2% of all cultures were positive for group A streptococci. The proportion of group A which was typable varied from 25.6 to 10% among the four schools serving high, middle and low socioeconomic white neighborhoods and a low socioeconomic black neighborhood. The most frequent serologic types were 12, 1, and 6. Carrier rates for both hemolytic and group A streptococci were about twice as high among black and white children from the two low socioeconomic schools as they were in the two higher socioeconomic schools. The proportion of positive cultures among children in the higher socioeconomic schools dropped markedly after the third school year, while those for children in lower socioeconomic schools remained the same. The reasons for this were thought to be closely related to factors influencing frequency of exposure to the hemolytic streptococcus.