THE PERSPECTIVES OF BOTH PROSECUTORS AND DEFENSE ATTORNEYS ON COOPERATION IN CRIMINAL CASE DISPOSITION ARE DISCUSSED IN LIGHT OF THE FINDINGS OF A MAIL SURVEY OF PROSECUTORS AND THEIR ASSISTANTS AND PUBLIC DEFENDERS IN ILLINOIS. THE DATA PRESENTED SUGGEST THAT THE STANDARDS FOR PLEA BARGAINING ARE FLEXIBLE AND VARY WITH THE CONTEXT OF THE CASE AND THE ATTITUDES OF THE DEFENSE AND PROSECUTING ATTORNEYS. THE DATA ALSO INDICATE THAT PROSECUTORIAL DECISIONS ARE BASED PRIMARILY ON EXTRALEGAL RATHER THAN LEGAL CONSIDERATIONS. A MAJORITY OF THE RESPONDING PROSECUTORS INDICATED THAT PERSONAL FACTORS INFLUENCED THEIR DECISIONS TO COOPERATE WITH CERTAIN ATTORNEYS. FOR EXAMPLE, 52 PERCENT SUGGESTED THAT THEY WERE LIKELY TO COOPERATE OR NEGOTIATE WITH DEFENSE ATTORNEYS WHO WERE PERSONABLE, FRIENDLY, COMMUNICATIVE, AND UNABRASIVE, OBSTINATE, OR OTHERWISE DIFFICULT. IN CONTRAST, ONLY 26 PERCENT OF THE DEFENDERS STRESSED THAT THE PERSONAL CHARACTERISTICS OF THE DEFENSE ATTORNEY WERE SIGNIFICANT FACTORS. WHILE PROSECUTORS COMMENTED ON THE IMPORTANCE OF HONESTY AND TRUST, PUBLIC DEFENDERS TENDED TO FEEL THAT FRIENDSHIP RESULTED IN GREATER COOPERATION. PUBLIC DEFENDERS CITED THREE ADDITIONAL FACTORS WHICH THEY FELT LED TO GREATER COOPERATION AND WHICH NONE OF THE PROSECUTORS MENTIONED, INCLUDING CONTINUING LIAISON, BENEFITS FOR THE PROSECUTOR, AND POLITICS. IT IS CONCLUDED THAT, INSTEAD OF BASING DECISIONS STRICTLY ON AUTHORITIVE LEGAL STANDARDS, THE PROSECUTOR OFTEN SUBSTITUTES PERSONAL STANDARDS FOR DISPOSING OF CRIMINAL CASES AND THAT SUCH STANDARDS ARE USUALLY DEVELOPED THROUGH GROUP INTERACTION AMONG JUDGES, PROSECUTORS, AND DEFENSE ATTORNEYS. THE STANDARDS APPLIED BY THE PROSECUTORS SEEM TO REFLECT A SHARED CONSENSUS AMONG PROSECUTORS AND DEFENSE ATTORNEYS ON THE NEED FOR COMPROMISE. A TABULAR BREAKDOWN OF THE PROSECUTOR'S AND PUBLIC DEFENDER'S PERCEPTIONS OF FACTORS WHICH INFLUENCE COOPERATION IS PROVIDED. REFERENCE NOTES ARE INCLUDED. (KBL)