For a number of years, the District of Columbia's Department of Public Health has been contending with tinea capitis infections among school children and their preschool siblings. From fewer than 500 new cases seen in the Ringworm Clinic of this department in the years 1949-1951, the number of new cases rose to a peak of 1,766 in 1956 (Figure). In order to cope with this increasing problem, two and one-half years ago the Department of Public Health in consultation with the Mycology Unit of the Communicable Disease Center of the United States Public Health Service developed an intensive case-finding and systematic followup program. Wood's-light surveys of students in the affected schools were initiated, and suspected cases were cultured at a central clinic and confirmed cases placed under treatment and closely supervised. Thereafter, a gradually rising incidence of infection that had begun in 1951 and which had