FOLLOWING A DISCUSSION OF CURRENT RESEARCH ON PROSECUTORIAL DISCRETION, THE METHODOLOGY OF A STUDY AIMED AT EXAMINING THE BASES FOR PROSECUTORIAL DECISIONMAKING IN PLEA NEGOTIATIONS IS DESCRIBED. THE METHODOLOGY USED WAS PATTERNED AFTER WILKINS' DECISION GAME AND IS SIMILAR TO THAT USED BY CARTER, SULLIVAN AND SIEGEL, AND SIEGEL, SULLIVAN, AND GREENE FOR STUDYING DECISIONMAKING PROCESSES AT OTHER STAGES OF THE CRIMINAL JUSTICE SYSTEM. TWO CASE HISTORIES WERE DEVELOPED WHICH REPRESENTED TWO TYPICAL SITUATIONS IN WHICH PROSECUTORS ARE CALLED UPON TO GRANT OR REFUSE CHARGING CONCESSIONS IN RETURN FOR A DEFENDANT'S OFFER TO PLEAD GUILTY--A HEROIN CASE, OFTEN CHARACTERIZED AS A VICTIMLESS OFFENSE, AND A RAPE CASE. A RANDOM SAMPLE (N-20) OF PROSECUTORS DRAWN FROM SEVERAL PROSECUTORIAL DISTRICTS IN THE NORTHEAST PARTICIPATED IN THE SIMULATED DECISIONMAKING DESIGNED TO REVEAL THE FOLLOWING: (1) THE VARIED TYPES AND AMOUNTS OF INFORMATION USED BY PROSECUTORS IN THE PLEA BARGAINING PROCESS, (2) THE RELATIVE WEIGHT ACCORDED TO TYPES OF INFORMATION IN DETERMINING WHETHER OR NOT TO REDUCE CHARGES AS PART OF A PLEA BARGAIN, (3) THE POINT AT WHICH DECISIONS ARE MADE AND THE NATURE OF THOSE DECISIONS, AND (4) THE DECISIONMAKING PATTERNS OR STYLES OF PROSECUTORS IN PLEA NEGOTIATIONS. DATA ANALYSIS REVEALED THAT THE ATTITUDE OF THE COMPLAINANT WAS THE MOST IMPORTANT FACTOR IN MAKING A DECISION. IN THE VICTIMLESS CASE INVOLVING HEROIN POSSESION, POLICE ATTITUDE WAS CHOSEN MOST OFTEN WHEN MAKING A DECISION. IN GENERAL, THE DATA SUGGEST THAT THE AMOUNT OF INFORMATION USED TO REACH DECISIONS AND THE TYPE OF DECISION REACHED VARY CONSIDERABLY AMONG PROSECUTORS IN THE PLEA BARGAINING CONTEXT. VARIABILITY DID NOT APPEAR TO BE RELATED TO SUCH FACTORS AS AGE, EXPERIENCE, OR OTHER PERSONAL VARIABLES. OF MORE IMPORTANCE WERE SUCH FACTORS AS THE DEFENDANT'S PRIOR RECORD, AGE, TYPE, STRENGTH, AND ADMISSIBILITY OF EVIDENCE, AND SENTENCING PROVISIONS. TABULAR DATA ARE INCLUDED, AND THE APPENDIX DESCRIBES THE CASES PRESENTED. (RCB)