A REVIEW OF RESEARCH ON THE EFFECTS OF JURY SIZE REVEALED LITTLE UNCONTESTED EVIDENCE. MANY OF THE METHODOLOGICAL SHORTCOMINGS PERVADING THESE STUDIES ARE APPARENTLY DUE TO THE SUBTLE NATURE OF SOME JURY-SIZE EFFECTS, AS WELL AS TO THE HIGHLY CRITICAL ATMOSPHERE IN WHICH THE ISSUE HAS DEVELOPED. GRADUALLY, THE ISSUE OF JURY SIZE HAS BROADENED FROM CONCERN WITH VERDICTS TO DIFFERENCES IN THE PROCESS OF JURY DELIBERATION. THE ISSUE HAS ALSO EXPANDED FROM AN EMPIRICAL INQUIRY TO THEORETICAL DEMONSTRATIONS. FOLLOWING THE SUPREME COURT'S DECISION ALLOWING NONUNANIMOUS JURIES, NUMEROUS MOCK TRIAL EXPERIMENTS SHOWED THAT SUCH JURIES WERE LESS LIKELY TO HANG THAN THOSE DELIBERATING UNDER A TRADITIONAL UNANIMITY RULE WHEN HEARING A CRIMINAL CASE. THE LACK OF EFFECT DUE TO DECISION RULE ON THE NEGLIGENCE AND AWARD DECISIONS OF CIVIL JURIES MAY REFLECT THE COMPROMISE INVOLVED IN AGREEING ON AN AMOUNT OF DAMAGES. A FEW STUDIES WHICH VARIED BOTH SIZE AND DECISION RULE OBSERVED NO SIGNIFICANT INTERACTION BETWEEN THE TWO VARIABLES. VARIOUS PREDICTIONS FROM THE MANY MODELS OF JURY DECISIONMAKING NOW AVAILABLE SUGGEST THAT THE EFFECTS OF DECISION RULE ARE LARGER THAN THOSE OF JURY SIZE, THOUGH NEITHER TENDS TO BE SIGNIFICANT. CONCEPTUALLY, SIZE AND RULE ARE INTERRELATED, NOT ONLY WITH ONE ANOTHER, BUT WITH THE PROBABILITY OF AN INDIVIDUAL VOTING FOR CONVICTION OR ACQUITTAL, THE NUMBER OF ALTERNATIVES, AND THE NATURE OF THE CASE. REFERENCES, GRAPHS, AND TABULAR DATA ARE INCLUDED. (AUTHOR ABSTRACT MODIFIED--RCB)