The analysis uses official Chicago Police Department data on calls for police service and crime reports filed by investigating officers in 74 community areas. Some of the ways in which official data on crime known to police can be used to evaluate police performance are discussed. By comparing demand for different kinds of police services, as measured by citizen calls for service, to the number of verified offenses recorded by the police, researchers analyze the level of 'unfounding' of incident reports and determine whether or not police decisions to unfound offenses affect particular segments of the population differently than they affect others. Overall, about 76 percent of calls for service for Part I personal crimes were recorded as verified offenses. About 83 percent of Part I property crimes were reported as verified crimes. Calls for service for Part II crimes were least likely to generate a verified crime; verified Part II offenses were about 64 percent of calls for service for this category over all 74 community areas. Not much variation was found among the communities for personal, property, or Part II crimes. Findings indicate that there is a considerable gap between calls for crime-related services as defined by citizens and verified crime reports as recorded by the police bureaucracy. Furthermore, these differences are related to the overall level of demand for police service and there is no evidence of any systematic discrimination against the 'urban under class' in police decisions to record incidents as verified crime. Data tables are included and 25 references are appended.