THE EDUCATION AND PROFESSIONAL BACKGROUND OF PSYCHOLOGISTS IS EXPLAINED, AND LICENSING REQUIREMENTS ARE CONSIDERED. FUNCTIONAL AND EDUCATIONAL DELINEATIONS BETWEEN PSYCHIATRISTS AND PSYCHOLOGISTS ARE NOTED. THE PSYCHOLOGIST HAS A KNOWLEDGE ABOUT A WIDER RANGE OF HUMAN BEHAVIOR, AND IS ORIENTED TOWARD RESEARCH. THEY HAVE EXPERTISE IN TESTING AND IN PSYCHOTHERAPY. GENERALLY, A PSYCHOLOGIST SHOULD BE ABLE TO TESTIFY OR BE USEFUL IN TRIAL WORK IN ONE OR MORE OF THESE AREAS: EVALUATION AND DIAGNOSIS PRESENTED BY THE OPPOSING SIDE; IN ANALYSIS OF A WIDE ARRAY OF HUMAN BEHAVIOR -- SUCH AS DECISIONMAKING, PORNOGRAPHY, AND DRUG USE -- WHICH PSYCHOLOGISTS HAVE STUDIED AND ON WHICH THERE IS A LARGE BODY OF PROFESSIONAL LITERATURE; AND IN SPECIFIC AREAS OF THE LAW, SUCH AS JURY SELECTION, JURY BEHAVIOR, EYEWITNESS TESTIMONY, AND INSANITY DEFENSE. APPLICATIONS ARE DISCUSSED. INSTRUCTIONS FOR LOCATING A PSYCHOLOGIST FOR COURTROOM WORK ARE PRESENTED. (DAG)