The objective in this paper is to describe and explain city-suburban disparities in expenditures for police protection. The question is whether cities have higher police expenditures than suburbs be­cause they face different conditions or because they respond differ­ently to those conditions. A model for the determination of police compensation and employment levels is specified and tested on 1979 data for 66 SMSA's with central city populations in excess of 100,000. The results of this analysis show that city-suburban disparities in per capita expenditures for police services are both pronounced and variable by region. In part the disparities are due to the greater need for police services in cities -- crime rate and population size exert important pressures on police spending in cities, but not in suburbs. In part, however, the disparities are due to institutional arrangements and policy choices -- unionization and local government structure.