The Five-Factor Model (FFM) is arguably the predominant model of general personality structure. There is a considerable body of research supporting its construct validity and practical application. There have been a few books specifically concerning the FFM, but to date there has not yet been a text that brings together in one location all that is known about the FFM. The book begins with an overview chapter on the FFM, followed by in-depth discussions regarding the nature, etiology, importance, and mechanisms of each of the FFM domains. The vast body of research concerning the construct-validity support for the FFM is then provided, including its robustness, factor analytic support, childhood antecedents, cross-language presence, cross-species presence, behavior and molecular genetics, and brain structure and function. The text then provides considerable discussion of the importance and application of the FFM across diverse social concerns, including personality assessment, business and industry, health psychology, marital-family therapy, adult psychopathology, child psychopathology, and clinical utility. There is no comparable text with this much information concerning the validity and utility of the FFM. The text concludes with a final overview chapter.