Career patterns of superintendents in 100 Illinois school districts in 1974-75 were traced over a 17-year period to examine turnover and career mobility patterns of public school superintendents. Information came from various state school directories and from Illinois Office of Education computer tapes. School districts were categorized according to size and type (elementary, secondary, unit), and the sample reflected size and type variations in the state's total population. More than 56% of the districts had fewer than 1,000 students; these districts had highest average number of superintendents, highest turnover rate (they accounted for 70.7% of turnovers), and lowest average number of years of service. As for mobility, each new academic year found some 16% of Illinois superintendents in a new position, two out of three of the superintendents were place-bound (staying in the same geographic region and district size and type), and most of those who moved exhibited horizontal rather than vertical mobility. Highest turnover rates were found in districts with fewer than 500 students. Future research should analyze the nature of small district turnover, develop training programs designed for those who want to serve smaller communities, and study characteristics of superintendents who appear as statistical outliers. (RS)