PREVIOUS RESEARCH INDICATED THAT JURORS EITHER DO NOT UNDERSTAND JUDGE'S INSTRUCTIONS OR THAT THEY IGNORE THEM. IN AN EFFORT TO INSTITUTE CLARIFY AND UNIFORMITY IN PRESENTING THE CHARGE TO A JURY, MANY STATES DEVELOPED PATTERN, OR STANDARDIZED, INSTRUCTIONS WHICH ALL JUDGES MUST USE FOR SPECIFIC TYPES OF CASES. THE EFFECTS AND PROBLEM AREAS OF PATTERN INSTRUCTIONS WERE ASSESSED THROUGH QUESTIONNAIRES GIVEN TO 116 PERSONS SUMMONED FOR JURY DUTY IN FLORIDA. THE PARTICIPANTS WATCHED VIDEOTAPED JURY INSTRUCTIONS FOR THE CRIME OF BREAKING AND ENTERING, THEN TOOK A COMPREHENSION TEST EMPHASIZING THE FOLLOWING: DEFINITION OF THE CRIME, CIRCUMSTANTIAL EVIDENCE, PRESUMPTION OF INNOCENCE, REASONABLE DOUBT, AND WITNESS CREDIBILITY. ONLY PERSONS WHO HAD NOT YET SERVED ON A JURY WERE USED FOR THE INSTRUCTED GROUP, AND THOSE WHO HAD BEEN ON A JURY THE PREVIOUS WEEK WERE ASSIGNED TO THE CONTROL GROUP. ANALYSIS OF THE DATA SHOWED THAT SUBJECTS WHO HAD RECEIVED THE INSTRUCTIONS SCORED SIGNIFICANTLY HIGHER THAN THE CONTROL GROUP, BUT THEY STILL UNDERSTOOD ONLY 72 PERCENT OF THE QUESTIONS. ITEM ANALYSIS INDICATED THAT COMPREHENSION WAS MOST DIFFICULT IN THE AREAS OF DEFINITION OF THE CRIME; THE TERMS INFORMATION, REASONABLE DOUBT, AND MATERIAL ALLEGATION; CONCEPTS OF REASONABLE DOUBT AND WITNESS CREDIBILITY. TABLE ILLUSTRATING THE DATA ON COMPREHENSION ARE INCLUDED. ADDITIONAL ANALYSIS SHOWED THAT PREVIOUS JURY EXPERIENCE, AGE, AND SEX DID NOT INFLUENCE COMPREHENSION AND THAT JURORS WITH SOME HIGHER EDUCATION SCORED BETTER ON THE TEST THAN THOSE WITHOUT COLLEGE TRAINING. (AUTHOR ABSTRACT MODIFIED-MJM)