Each day, we make judgments about the personality characteristics of those around us, and we routinely rely on them to guide our behavior in interpersonal interactions and relationships. This handbook provides a review of theory and research on the accuracy of personality judgments. After a historical review, the first section presents the major theoretical models that guide research in this area and describes methodological approaches to evaluating accuracy. The second section reviews the research findings relevant to four moderators of accuracy, and the third section focuses on judgments people make of themselves. The fourth section examines various types of information used in making personality judgments, while the fifth section provides examples of some of the domains to which accuracy research can be applied, including romantic relationships and clinical practice. Learning about the process of accurate judgments can be used to help people understand when and how they are more likely to make accurate judgments, and this handbook offers a thorough, evidence-based, and up-to-date review of this research field.