Such 'community mapping' rests on four major assumptions. The role of police must be defined both broadly and at the street level. The public has ascertainable needs. Police administrators cannot rely solely on their experience and judgment to obtain citizen information and incorporate it into agency outputs. Finally, the public cannot be expected to come forward to express its concerns voluntarily; and if citizens do so, concerns will be expressed differentially and may not represent the entire community. Carefully planned and executed survey sampling methods provide a means for learning more about the needs and attitudes of clients that are necessary to formulate law enforcement policy. This will ensure that the sample is not biased or unrepresentative. Such information permits greater democracy in the often bureaucratic police organization, increases agency responsiveness to the public, supports proactive policing, and enhances community relations. 18 references.