This definitive volume lays the foundations for an interdisciplinary science of personality. Leading investigators present novel insights and findings from molecular genetics, child and life-span developmental psychology, neuroscience, dynamical systems theory, evolutionary psychology, and social cognition, as well as personality psychology itself, illuminating--and often reformulating--fundamental questions about the nature of personhood. The book sheds new light on the nature and origins of personality and individual differences, and challenges many traditional assumptions. It also points toward compelling new directions for future work in the field.