OBSERVATION, UNSTRUCTURED AND 'SEMISTRUCTURED' INTERVIEWS, SECONDARY DATA ANALYSIS, AND DOCUMENT ANALYSIS WERE USED TO DEVELOP THE CASE STUDIES. ENOUGH DIFFERENCES WERE FOUND BETWEEN THE TWO INSTITUTIONS TO FORMULATE A HYPOTHESIS CONCERNING THE CONTROL OVER THE FLOW OF CLIENTS BETWEEN POLICE AND COURTS, THE VARIABLES WHICH AFFECT THIS FLOW, AND THE CONSEQUENCES OF VARIATIONS. INTERACTIONS BETWEEN POLICE DEPARTMENTS AND JUVENILE COURTS ARE DESCRIBED AS 'TRANSACTIONS OF CASES,' MEANING THE INFORMATION ESSENTIAL FOR CASE PROCESSING, AND 'TRANSACTIONS ABOUT CASES,' ACTIVITIES NOT ESSENTIAL TO CASE PROCESSING WHICH CAN SHAPE SUBSEQUENT CASE OUTCOMES. IN THE URBAN AREA, POLICE INFLUENCE OVER COURT CASES GRADUALLY DECLINED DURING THE STUDY PERIOD. WHILE IN THE MEDIUM-SIZED CITY IT INCREASED. FACTORS RESPONSIBLE FOR THE DECLINE INCLUDED DECREASED FUNDING FOR A YOUTH SERVICES BUREAU, A FEELING BY THE DETECTIVES THAT THE COURT DID NOT WANT DETAILED SCREENING, AND, FINALLY, A LETTER FROM THE DIRECTOR OF JUVENILE SERVICES REQUESTING PATROL OFFICERS TO TAKE APPREHENDED JUVENILES DIRECTLY TO JUVENILE INTAKE. MEANWHILE, THE MEDIUM-SIZED CITY WAS SETTING UP A JOINT POLICE-COURT COMMITTEE TO ENCOURAGE GREATER POLICE PARTICIPATION IN JUVENILE SCREENING. THE ORGANIZATIONAL FACTORS WHICH INFLUENCE THE FLOW OF JUVENILE CASES ARE DISCUSSED. THE INTERDEPENDENCE OF THE DIFFERENT BRANCHES OF THE JUVENILE JUSTICE SYSTEM IS EMPHASIZED. FLOW CHARTS AND TABLES SUMMARIZE THE CASE STUDY DATA. REFERENCES ARE APPENDED. (GLR)