The author argues that significant advances in police performance measurement can be achieved by focusing on what police officers do and accomplish within the time span of their encounters with the public. After reviewing the limitations of the kinds of performance measures that have been and are in fashion, the paper suggests that performance measures pertinent to crime and disorder rates, citizen perceptions, and other indicators of quality of life ignore some of the aspects of policing that are of primary concern for citizens. These aspects relate to how the police treat the public in their daily encounters and the public's immediate response. The author discusses a number of dimensions of performance in such encounters and describes ways to collect data. Also discussed are ways to involve police master craftsmen, social scientists, and others in this process. The dimensions of performance in police- citizen encounters include violence containment and disorder control, problem diagnosis, problem resolution, citizen response to police, people's safety, the lawfulness of the police response, and economy in police response. Data-collection sources include officers' self-reports, reports of citizen participants, evaluations by other professionals, video recording, and third- party direct observation. Topics considered in the concluding section of the paper are a process for the development of evaluation criteria, the design of evaluation instruments, and data interpretation. 60 references and 13 notes