THE CONTEXTS IN WHICH 'DEFINING OF SITUATIONS' ARE EXAMINED CONSIST OF THE OFFICER IN THE FIELD, THE OFFICER ORIENTING HIM/HERSELF TO THE POLICE ORGANIZATION, THE UTILIZATION OF REPORT FORMS AS GUIDES FOR INVESTIGATIVE ACTIVITY, AND THE EMPLOYMENT OF REPORTS AS A MEANS OF PERSUASION. AS POLICE OFFICERS CONSTRUCT DEFINITIONS OF SITUATION IN EACH OF THESE CONTEXTS, THEY RELY ON PRACTICAL KNOWLEDGE ACQUIRED THROUGH FORMAL EDUCATION AND EXPERIENCE, ORGANIZATIONAL RULES, COMMANDS AND POLICIES, INSTRUCTIONS EXPLICITLY OR IMPLICITLY PROVIDED ON REPORT FORMS, AND LAWS, BOTH LEGISLATIVE AND JUDGE-MADE. IF ONE VIEWS THESE NORMATIVE ELEMENTS AS DEMANDING PARTICULAR DEFINITIONS OF THE SITUATION OR COURSES OF ACTION, IT IS CLEAR THAT THE POLICE FREQUENTLY BREAK THE RULES, AVOID POLICY, IGNORE WHAT THEY HAVE LEARNED, AND FAIL TO ENFORCE THE LAW. HOWEVER, IT IS PROPOSED THAT RULES, PROCEDURES, AND LAWS, SHOULD NOT BE TAKEN LITERALLY. RATHER THEY SHOULD BE REGARDED AS TYPIFIED KNOWLEDGE OR SCHEMES OF INTERPRETATION THAT ENABLE THE POLICE TO MAKE SENSE OF THE DIVERSE AND UNIQUE ELEMENTS WHICH MAKE UP ENCOUNTERED SETTINGS. THE PROCESS OF DEFINING SITUATIONS IS FURTHER COMPLICATED BECAUSE TYPIFIED KNOWLEDGE SERVES AS A SCHEME OF INTERPRETATION AND ALSO TAKES ON UNIQUE MEANINGS. FINALLY, IT IS ASSERTED THAT, WHEN USED AS A BASIS OF A COURSE OF ACTION, DEFINITIONS OF THE SITUATION CONSTITUTE TYPIFIED KNOWLEDGE. THIS ASSERTION THEN SERVES AS A BASIS FOR THE REEVALUATION OF THE STATEMENT THAT THE POLICE MUST 'PLAY IT BY EAR' AND THE ASSUMPTION THAT THE EXERCISE OF POLICE DISCRETION INVOLVES A TWO-STEP PROCESS. REFERENCES AND METHODOLOGICAL INFORMATION ARE APPENDED. (AUTHOR ABSTRACT MODIFIED).