The paper outlines a new and broadly inclusive conceptual itinerary for the scientific study of personality development across the human life course. From the standpoint of the person as a social actor, a first line of development runs from the temperament dimensions observed in infancy through the establishment of adult personality traits, tracking a movement toward greater elaboration and regulation of the person’s socio-emotional performance style. A second line of development traces continuity and change in the motivated agent, running from the child’s consolidation of theory of mind, through an age 5–7 shift, to the articulation in adolescence and adulthood of life goals and values. From the perspective of the autobiographical author, a third line of personality development runs from the sharing of episodic memories between preschool children and their parents to the emergence of autobiographical reasoning skills in adolescence, ultimately resulting in the construction of an integrative life story, or narrative identity. The itinerary expands the purview of personality development beyond the canonical trait concept to encompass contemporary theories and findings in evolutionary psychology, sociology, and motivational psychology, as well as the study of cognitive development in children, moral development, political orientations, religious attitudes and practices, autobiographical memory, and the master narratives of culture.