A LEADING COURT CASE HAS HELD THAT A GROUP IS COGNIZABLE IF IT HAS A DEFINITE COMPOSITION, IS COHESIVE, AND ITS EXCLUSION MIGHT RESULT IN BIAS BY JURIES HEARING CASES INVOLVING YOUNG CRIMINAL DEFENDANTS. YOUNG ADULTS AS A GROUP ARE SUBSTANTIALLY UNDERREPRESENTED ON JURIES AND, IN SOME JURISDICTIONS, ARE VICTIMS OF OVERT DISCRIMINATION. TO EXAMINE THE COGNIZABILITY OF YOUNG ADULTS, A SURVEY WAS CONDUCTED IN QUEENS COUNTY N.Y., TO EXAMINE ATTITUDES ABOUT THE OPERATION OF THE CRIMINAL JUSTICE SYSTEM AND SERVICE ON PETIT AND GRAND JURIES. THE QUESTIONNAIRE CONTAINED 21 OPINION STATEMENTS AND REQUESTED DEMOGRAPHIC INFORMATION. IN ALL 579 INTERVIEWS WERE COMPLETED. FINDINGS WERE STATISTICALLY ANALYZED IN RELATION TO AGE, NONWHITE RACE, FEMALE SEX, OCCUPATION, AND INCOME. AGE WAS THE MOST IMPORTANT CHARACTERISTIC IN OPINION STATEMENTS OF PETIT JUROR RESPONDENTS AND THE SECOND MOST IMPORTANT SOCIAL CHARACTERISTIC FOR GRAND JURY RESPONDENTS. THERE WERE SIGNIFICANT DIFFENCES IN ATTITUDES BETWEEN YOUNGER AND OLDER PERSONS FOR NEARLY ALL OF THE 21 OPINION STATEMENTS. DIFFERENCES IN ATTITUDES GENERALLY PROGRESSED SYSTEMATICALLY FROM THE YOUNGEST TO THE OLDEST AGE GROUPS. IN MOST CASES, THE GREATEST DIFFERENCES IN ATTITUDES OCCURED BETWEEN THE YOUNGEST AND THE OLDEST AGE GROUPS. CORRELATIONS BETWEEN AGE AND ATTITUDES WERE STRONGER THAN CORRELATIONS BETWEEN RACE, SEX, OCCUPATION, OR INCOME AND ATTITUDES. IT IS CONCLUDED THAT YOUNG ADULTS ARE A COGNIZABLE GROUP WHICH SHOULD BE ADEQUATELY REPRESENTED ON JURIES. THE HISTORY OF GROUP COGNIZABILITY IS TRACED, AND DIFFERENT APPROACHES COURTS HAVE TAKEN TO COGNIZABILITY ARE NOTED. CASE LAW CONCERNING TRADITIONAL CRITERIA OF COGNIZABILITY AND THE COGNIZABILITY OF YOUNG ADULTS IN PARTICULAR ARE EXAMINED. APPENDIXES CONTAIN A DESCRIPTION OF THE SURVEY METHODOLOGY, THE SURVEY INSTRUMENT, AND INFORMATION ON STATISTICAL WEIGHTING PRODUCES EMPLOYED IN THE ANALYSIS OF SURVEY RESULTS. SUPPORTING DATA ARE INCLUDED. (DEP)