This second edition of the bestselling textbook Personality Traits is an essential text for students doing courses in personality psychology and individual differences. The authors have updated the volume throughout, incorporating the latest research in the field, and added three new chapters on personality across the lifespan, health and applications of personality assessment. Personality research has been transformed by recent advances in our understanding of personality traits. This book reviews the origins of traits in biological and social processes, and their consequences for cognition, stress, and physical and mental health. Contrary to the traditional view of personality research as a collection of disconnected theories, Personality Traits provides an integrated account, linking theory-driven research with applications in clinical and occupational psychology. The new format of the book, including many additional features, makes it even more accessible and reader friendly.