The study was conducted between March 1975 and January 1976 and involved citizen observers accompanying patrol officers as they responded to citizens' calls for help. Citizens were interviewed; events were recorded on tape and compared with official reports of the incidents. Approximately 7,000 incidents were reported over the study period. The study found that 62 percent of the incidents were discovery crimes, which are not susceptible to rapid police response. Although 38 percent were involvement crimes with the reporting person present at the occurrence, reporting delays were frequent and influenced by citizen apathy and scepticism toward police crime-solving abilities. Citizen reporting time was a primary determinant of response time. A rapid police response is desirable for violent involvement crimes (including burglaries), but these constituted only 25 percent of the calls. In some cases calls were made after delays of several hours; on the average, almost half of the response time was citizen rather than police time. This indicates the relative unimportance of striving for reductions of seconds through use of crime alert telephone numbers or additional manpower and technology. Instead, procedures must be developed for discriminating emergency and nonemergency calls for clarifying the reasons why citizens do not respond faster.