This is a study of the relationship between the amount of time taken by police to respond to calls for service and the outcomes of criminal and noncriminal incidents in Kansas City, Missouri. Outcomes were evaluated in terms of police effectiveness and citizen satisfaction. Response time data were generated by timing telephone and radio exchanges on police dispatch tapes. Police travel time was measured and recorded by highly trained civilian observers. To assess satisfaction with police service, personal and telephone interviews were conducted with victims and witnesses who had made the calls to the police.