This study examines the demand for teachers, the mobility of teachers, and the relationship between school district size and the level of costs/expenditures on education. The material focuses on individual school districts and on the implications of district behavior that are developed from the economics theory of the firm. Examination of the teacher demand by use of a stock-adjustment model suggests that roughly half the difference between the desired stock of teachers and the actual stock will be made up in any one school year and that the sole factor with considerable impact on the desired stock is pupil enrollment. A human capital approach was used to examine the mobility of teachers across school districts. Experience, age, and training distributions of teachers were the teaching force characteristics most significantly related to turnover, and turnover appears higher in those districts having a greater proportion of young teachers with little experience. In general, it was found that the greater the district size and the greater its growth rate the smaller was the turnover. Findings indicate there appear to be economies of scale in the operation of school districts. A 20-item bibliography concludes the document. (Author)