Book excerpt: How do individual differences interact with situational factors to shape social behavior? Are people with certain traits more likely to form lasting marriages; experience test-taking anxiety; break the law; feel optimistic about the future? This handbook provides a comprehensive, authoritative examination of the full range of personality variables associated with interpersonal judgment, behavior, and emotion. The contributors are acknowledged experts who have conducted influential research on the constructs they address. Chapters discuss how each personality attribute is conceptualized and assessed, review the strengths and limitations of available measures (including child and adolescent measures, when available), present important findings related to social behavior, and identify directions for future study.