This paper poses the following question: When, in spite of knowing that it is wrong, people go on to hurt others, what does this mean for the development of moral agency? We begin by defining moral agency and briefly sketching relations between moral agency and other concepts. We then outline what three extant literatures suggest about this question: social domain theory, moral intuitionist theories, and theories of moral identity development. Building on these literatures, but moving beyond them, we propose that experiences of harming others are catalysts for the development of what we term moral agency. In the remainder of the paper, we outline a model for how moral agency develops that draws on research about the narrative development of self. We close by outlining some of the critical directions for future work that are suggested by our approach.