This discussion paper, published jointly with the National Institute of Justice, summarizes prior research on police use of force and lists the difficulties inherent in collecting use-of-force data, including definitional problems, reluctance of police agencies to provide reliable data, concerns about the misapplication of reported data, and the degree of detail needed on individual incidents. It also discusses alternative approaches to data collection and sources of data, including official records, surveys of police, and surveys of citizens. The paper concludes that it will be some time before a national reporting program is implemented. In the meantime two pilot programs are collecting data on use of force: an expansion of the BJS National Crime Victimization Survey to include questions about use of force and a grant to the International Association of Chiefs of Police for the first phase of a four-phase program to establish a national database to collect incident reports on use of force from police departments. This report was prepared by Tom McEwen of the Institute for Law and Justice.