QUESTIONNAIRES WERE ADMINISTERED TO 247 POLICE AND PROSECUTORS ATTENDING A CONFERENCE ON POLICE-PROSECUTOR RELATIONS. THE FIRST SECTION OF THIS ARTICLE EXAMINES THE DATA ON WHETHER PROSECUTORS AND POLICE TRANSMIT ADVICE TO EACH OTHER ON JOINT AGENCY PROBLEMS. THE INQUIRY REVEALS THAT THE TWO AGENCIES COOPERATE TO A GREATER OR LESSER DEGREE, LARGELY DEPENDING ON THE SPECIFIC PROBLEM INVOLVED. THE SECOND SECTION COVERS THE TRANSACTIONS IN WHICH POLICE AND PROSECUTORS INEVITABLY MAKE CONTACT. IT DESCRIBES THE LIKELY SOURCES OF TENSION AND FRICTION BETWEEN THE TWO AGENCIES IN SETTINGS SUCH AS CASE SCREENING, POLICE TRAINING, AND TRIAL PREPARATION. THE THIRD SECTION DISCUSSES REASONS UNDERLYING THE CONFLICT AND DESCRIBES CHICAGO'S FELONY REVIEW UNIT AS THE PANACEA FOR MANY OF THE IMPEDIMENTS TO EFFECTIVE INTERAGENCY COOPERATION. (AUTHOR ABSTRACT MODIFIED)