IN CHICAGO, CRIME AND THE CRIMINAL JUSTICE SYSTEM WERE ROOTED IN THE CITY'S ETHNIC IMMIGRANT NEIGHBORHOODS. BOTH WERE A MEANS OF UPWARD SOCIAL MOBILITY FOR PERSONS OF MARGINAL SOCIOECONOMIC POSITION, AND CONSEQUENTLY CRIMINALS, POLITICIANS, AND ENFORCEMENT OFFICIALS OFTEN SHARED EXPERIENCES AND VALUES. MOST OF THOSE PROCESSED THROUGH THE CRIMINAL JUSTICE SYSTEM WERE THE UNORGANIZED OFFENDERS: JUVENILE DELINQUENTS, DRUNKARDS, WIFE-BEATERS, AND AMATEUR THIEVES. THE ORGANIZED UNDERWORLD, UNDER THE LEADERSHIP OF ETHNICS (IRISH, JEWISH, ITALIAN, AND BLACK), CONSISTED OF PROFESSIONAL THIEVES, LABOR AND BUSINESS RACKETEERS, AND PARTICIPANTS IN ORGANIZED CRIME. IN MANY WAYS ORGANIZED CRIMINAL ACTIVITY RESEMBLED A BUSINESS WITH CAPITAL INVESTMENTS, PAYROLLS, DISTRIBUTION, AND RETAILING FUNCTIONS. ORGANIZATION AND CONSOLIDATION WERE EXTENSIVE, AND UNDERWORLD FIGURES HELD IMPORTANT POLITICAL AND CIVIC POSITIONS. IN ADDITION TO RELATIONSHIPS BASED ON MUTUAL INTERESTS AND FAVORS, YOUTHFUL FRIENDSHIPS AND SHARED ETHNIC SOCIAL LIFE LINKED POLITICIANS, LAW ENFORCEMENT OFFICIALS, LEGITIMATE BUSINESSMEN, AND GANGSTERS. IN ATTEMPTING TO ALTER THE CRIMINAL JUSTICE SYSTEM, REFORMERS FACED OPPOSITION STEMMING FROM PUBLIC DEMAND FOR UNDERWORLD SERVICES, ETHNIC AND CLASS LOYALTIES, AND THE ENTRENCHED RELATIONSHIPS OF CRIMINALS WITH THE POLITICAL AND CRIMINAL JUSTICE SYSTEMS. NATIVE-BORN, ANGLO-AMERICAN, UPPER CLASS, AND PROTESTANT, THESE REFORMERS DIFFERED IN VALUES AND LIFE EXPERIENCES FROM CHICAGO'S ETHNIC POWER ELITE. THE GOALS OF THE REFORMERS INCLUDED EFFICIENCY, ELIMINATION OF CORRUPTION AND FAVORITISM, AND CREATION OF A MORE MORAL URBAN ENVIRONMENT. WORKING TO THE REFORMERS' ADVANTAGE WAS THEIR RELATIVE WEALTH, NORMATIVE VALUES, SOCIAL PRESTIGE, ORGANIZATIONAL SKILLS, AND CONTROL OF THE NEWSPAPERS. REFORM EFFORTS WERE SUCCESSFUL IN ESTABLISHING A REHABILITATION-ORIENTED JUVENILE COURT IN COOK COUNTY. HOWEVER, REFORM EFFORTS AIMED AT THE ADULT CRIMINAL JUSTICE SYSTEM WERE LESS SUCCESSFUL. EFFORTS TO CLEAN UP COMMERCIALIZED VICE AND THE DICRETIONARY ADMINISTRATION OF THE COURTS WERE LARGELY INEFFECTIVE. HERE, THEIR DEMANDS CONFLICTED WITH THE VESTED INTERESTS OF THE UNDERWORLD AND THE POLITICAL AND CRIMINAL JUSTICE SYSTEMS. AS OUTSIDERS, THE REFORMERS HAD LITTLE IMPACT ON THE INFORMAL PATTERNS AND INTERRELATIONSHIPS OF THE ETHNIC INSIDERS. NOTES ARE PROVIDED. (JAP)