THE RESEARCH IS BASED ON THE PREMISE THAT VARIATION IN LAW ENFORCEMENT ACTIVITY CANNOT BE EXPLAINED SOLELY BY DIFFERING CRIME RATES AMONG CITIES. EQUATION FACTORS WERE DERIVED FROM THE THEORY THAT THE ACTIVITY OF AN ORGANIZATION IS LARGELY DERIVED FROM WHETHER IT IS AN OPEN SYSTEM (RESPONSIVE TO THE INFLUENCES OF THE ENVIRONMENT IN WHICH IT OPERATES) OR A CLOSED SYSTEM (ORGANIZATIONAL GOALS SET INDEPENDENT OF ENVIRONMENTAL CHARACTERISTICS). TO EXAMINE VARIATION IN ARREST POLICIES, DATA WERE COLLECTED FROM 40 OF 42 U.S. CITIES WITH POPULATIONS FROM 300,000 TO 1,000,000. THE MAJOR FOCUS OF THE STUDY WAS ON EXPLAINING ARREST VARIATION FOR CERTAIN MISDEMEANOR OR PART II CRIMES, SINCE PREVIOUS RESEARCH SUGGESTS AN INVERSE RELATIONSHIP BETWEEN THE SERIOUSNESS OF A CRIME AND THE EXERCISE OF POLICE DISCRETION. ARREST DATA FOR A NUMBER OF PART I OFFENSES ALSO ARE INCLUDED, HOWEVER. INDEPENDENT VARIABLES USED WERE CRIME ENVIRONMENT (INCOME INEQUALITY, PERCENT NONWHITE, MALES AGE 15-19), POLITICAL CULTURE (PERCENT WHITE COLLAR, FOREIGN-BORN, OR MIXED PARENTAGE, LEAGUE OF WOMEN VOTERS MEMBERSHIP), REGION (SOUTH-NONSOUTH), AND ECONOMIC INTERESTS (RETAIL SALES, CHAMBER OF COMMERCE MEMBERSHIP), ALL OF WHICH CONSTITUTED ENVIRONMENTAL VARIABLES. ORGANIZATIONAL INDEPENDENT VARIABLES USED WERE CENTRALIZATION (POLICE STATIONS), SPECIALIZATION (PERCENT OF FORCE ASSIGNED TO SPECIALIZED NONPATROL DUTIES), PROFESSIONALISM (SALARY CHIEF, COLLEGE INCENTIVE PAY), COMMUNITY RELATIONS ORIENTATION (COMMUNITY RELATIONS TRAINING), AND TASK ORIENTATION (AREAS COMPUTERIZED, HELICOPTERS PER CAPITA). WHILE THERE ARE SOME EXCEPTIONS, RESULTS SHOW THAT INDICATORS OF A CITY'S CRIME ENVIRONMENT ARE POSITIVELY RELATED TO ARREST RATES, WITH PERCENT NONWHITE POPULATION BEING THE MOST IMPORTANT PREDICTOR VARIABLE. HOWEVER, OTHER CATEGORIES OF VARIABLES ARE NOT UNIMPORTANT IN EXPLAINING ARREST RATES. OVERALL, THE FINDINGS SUGGEST THE IMPORTANCE OF CONCEPTUALIZING POLICE DEPARTMENTS AS OPEN SYSTEMS. TABULAR DATA ARE PROVIDED. (RCB)