In this study a model of the relationship between urbanization, school system variables and the sex composition of the teaching profession is developed. In the cross sectional analysis of data from 1870, the relationship between urbanization and the feminization of this occupation is explained in terms of length of the school year, the enrollment of a higher proportion of school age children, the more formalized control of the school, and the relative inexpensiveness of female labor. However, in a longitudinal analysis through the year 1875, it is shown that employers were not responding solely to the economic incentives of female labor, but rather, were influenced by past hiring patterns. The process through which the intermediate variables (length of year, percent enrolled, bureaucratization) and urbanization influenced feminization of the teaching profession is obscured since these factors are interrelated. (Author/GC)