The purpose of this project is to identify the social forces and public policies associated with varying rates of homicide by police officers. The project will analyze three sources of data on police homicides: statistics on coroners' reports from the 56 largest cities and all 50 States, official reports in two police departments, and previously unanalyzed raw data from earlier studies. The project will initially examine the reliability of the data sources and the appropriateness of different bases for computing rates of police homicide. Variation across cities in the characteristics of police homicide incidents will then be examined as a foundation for a longitudinal and cross-sectional analysis of police homicide rates. Among the 25 or more independent variables to be examined are unemployment, racial and age composition of cities, income inequality, police department weapon size and shooting policies, and State laws restricting or justifying police use of deadly force.