DATA COLLECTION AND ANALYSIS FOCUSED ON 201 FELONY CASES TRIED BY JURY IN MARION COUNTY, INDIANA, BETWEEN JANUARY 1974, AND JUNE 1976. THE DATA PROVIDED A PRELIMINARY INDICATION OF THE TRIAL FACTORS AFFECTING JURORS' DECISIONS. VERDICTS WERE BASED ON THE EVIDENCE PRESENTED, BUT NOT ALL EVIDENCE WAS ACCORDED THE SAME WEIGHT. THE AMOUNT OF TESTIMONY AND WHETHER ITS SOURCE WAS THE DEFENDANT OR AN ACCOMPLICE APPEARED ESPECIALLY PERSUASIVE. IN CONTRAST, JURIES DID NOT RELY SIGNIFICANTLY ON EYEWITNESS IDENTIFICATION, EXPERT TESTIMONY, OR VICTIM TESTIMONY, PERHAPS BECAUSE THEY CONSIDERED SUCH TESTIMONY PRONE TO FALLACY. JURY DECISIONS TENDED TO BE ADVERSE WHERE THE DEFENDANT WAS DISCREDITED OR DISCREDITABLE. JURIES EXERCISED THEIR DISCRETION IN DEPARTING FROM INSTRUCTIONS ONLY IN CERTAIN CIRCUMSTANCES. CONVICTION WAS MORE LIKELY IF THE VICTIM WAS YOUNG OR THE DEFENDANT WAS UNEMPLOYED, ALTHOUGH NEITHER OF THESE FACTORS WAS MENTIONED IN JURY INSTRUCTIONS OR THE LAWS AT ISSUE IN THE CASES. THERE WAS A RELUCTANCE TO CONVICT WHERE THE CRIME WAS SERIOUS, INDICATING PERHAPS THAT PRESCRIBED PUNISHMENTS MAY BE EXCESSIVE. THESE FINDINGS OF SUBSTANTIAL RULE DEPARTURES BY JURIES IN CERTAIN CIRCUMSTANCES SUGGEST THAT THE JURY ROLE IS NEITHER CLERKLIKE NOR EXCESSIVELY DISCRETIONARY. TABULAR DATA AND REFERENCES ARE PROVIDED. (RCB)