The three major groups of law enforcement statistics at the local, State, and Federal levels of aggregation are defined: input data (calls for service and crimes reported), process data (number of agencies, functions, personnel, expenditures, etc.), and output data (arrests, clearances, convictions, citizen attitudes, and use of deadly force). The historical development of the collection of law enforcement statistics is traced, and national data collection efforts conducted by the International City Manager's Association, the International Association of Chiefs of Police, Fraternal Order of Police, Kansas City Police Department, Police Foundation, and Police Executive Research Forum (PERF) are examined. The research that used these data is explored, and the results of two users' surveys are reported. The first survey, conducted by PERF, questioned 152 large police departments about the utility, availability, and sources of statistics for those agencies. The second survey, conducted by the Institute of Criminal Justice and Criminology at the University of Maryland, involved telephone interviews with searchers and policymakers concerning their uses of law enforcement statistics. Recommendations for obtaining law enforcement administrative statistics on a national scale are presented. Ten tables, 7 appendixes, and approximately 45 references are included.