Relevant data were collected from the York Bureau of Police Incident Reports for September through December 1976. About 8,788 calls for service were received during that period; however, the 1,284 cases analyzed in this study involved only the 'serious' calls or crimes that warranted a detailed report and investigation. Burglary, theft, automobile theft, vandalism, robbery assault, and aggravated assault were the most frequent major offenses for the study period. Bivariate relationships of clearance rate to crime, suspect, and operational variables were examined, and discriminant function analysis was conducted to help ascertain what independent relationships the examined variables have to crime clearance. The findings clearly show that witness presence and suspect description are the most critical variables in producing apprehension. Less than 1 percent of the cases for which a suspect is not described are cleared, and 25 percent of the cases with a witness present are cleared, compared to only 9 percent clearance of the cases with no witness present. Although the police have no control over whether or not a crime was committed in the presence of a witness, the police can increase apprehension by ferreting out witnesses who are reluctant to come forward and by developing styles of interaction with witnesses that will encourage their effective cooperation. In addition, the assignment of investigatory reponsibility for major incidents to the officer responding to the call may enhance citizen cooperation. Rather than merely completing a report, the officer on the scene would obtain witnesses and witness information, do followup investigations, and receive formal recognition for fulfilling these important responsibilities. Tabular data and 17 footnotes are provided.