Every significant piece of public policy, every important generalization in history, economics, political science, and sociology depends on (largely unevaluated) assumptions about human nature. Personality psychology concerns the nature of human nature; it is, therefore, concerned with one of the most powerful and dangerous forces on earth. Developing adequate methods for conceptualizing human nature and forecasting significant components of social behavior—for example, integrity, creativity, leadership—would seem to be a matter of real urgency. Nonetheless, personality psychology has a minor and marginal status in academic psychology. I have spent my career trying to understand the origins of human behavior, trying to develop measurement models for capturing key elements of social performance, and trying to defend the study of personality against the complaints of a seemingly endless supply of academic critics.