Moral identity theory and research emerged in the early 1980s and the field has grown ever since. In this chapter, the authors begin by reviewing the history of work on moral identity. They provide a framework for thinking about moral identity grounded in McAdams’s three levels of personality: traits, characteristic adaptations, and live narratives. Then the authors review research on moral identity development across the life span at these three levels of personality. Next, they review work on contexts of moral identity development, based on Bronfenbrenner’s ecological model: family, peers, schools, communities, cultures, media, and religion. Last, the authors outline five questions for future research.