A discussion of the constitutional guarantees to a trial by jury is followed by a historical overview which focuses on the jury's roots in ancient civilizations and English law. The guide notes that most States retain 12-member juries, although size differs in civil trials and in grand juries. It addresses distinctions between the grand jury and the petit jury, how jurors are summoned, who is eligible for jury selection, jury rolls, and the question of how representative a jury pool will be. The section on choosing a jury explains voir dire, attorneys' right to challenge potential jurors, abuses of peremptory challenges, grand jury selection, and jury research. The jury's job is to decide the case only on the facts presented in the courtroom. The booklet explores the meaning and implications of this purpose, the juror's obligations, how a jury decides, common jurors' complaints, jurors' rights, and whether the jury has the right to nullify or reinterpret the law. The final sections review a jury's sentencing powers, the workings of a grand jury, and criticisms of the present system such as it being too time-consuming and inefficient or incapable of handling complex civil cases. Other reforms examined involve jury pools, voir dire, and inefficient use of jurors' time. The use of juries in other countries is described. Resource organizations and selected references are listed.