THE OPENING DISCUSSION REVIEWS LITERATURE DOCUMENTING ARGUMENTS FOR AND AGAINST PLEA BARGAINING, DESCRIBES THE VARIOUS FORMS OF PLEA BARGAINING, AND CITES HISTORICAL STUDIES OF PLEA BARGAINING. THE ANALYSIS OF INITIAL AND CHANGED PLEAS OF GUILTY IN ALAMEDA COUNTY SUPERIOR COURT SINCE 1880 SUGGESTS THAT PLEA BARGAINING HAS BEEN PRESENT SINCE THE COURT'S BEGINNING AND THAT THE FORM OF BARGAINING HAS CHANGED OVER THE COURSE OF THE PERIOD EXAMINED. PLEA BARGAINING APPARENTLY WAS NOT UNUSUAL IN THE 19TH CENTURY; HOWEVER, NEITHER THEN NOR IN THE FIRST DECADES OF THE 20TH CENTURY WAS PLEA BARGAINING DOMINANT. IT WAS ONLY AFTER WORLD WAR II THAT PLEA BARGAINING WAS FORMALLY USED IN THE MAJORITY OF FELONY CASES. THE DATA ALSO SUGGEST THAT BOTH IMPLICIT AND EXPLICIT BARGAINING HAVE EXISTED SINCE 1880 BUT THAT IMPLICIT BARGAINING IS BEING REPLACED BY EXPLICIT BARGAINING. THE TREND IN MORE RECENT YEARS IS FOR DEFENDANTS TO PLEAD NOT GUILTY INITIALLY, BARGAIN, CHANGE THEIR PLEAS, AND PLEAD GUILTY TO LESSER OR FEWER CHARGES. IMPLICATIONS OF THE FINDINGS FOR PROPOSED REFORMS IN PLEA-BARGAINING PRACTICES ARE DISCUSSED. SUPPORTING TABULAR DATA ARE INCLUDED. (LKM)