This paper aims at connecting Self-Determination Theory (SDT) with research on moral identity. It is argued that SDT provides a unique and integrative framework for addressing important questions that have guided research on moral identity for many years: What is a moral identity? How is it linked to moral action? How do moral identities develop? In the present paper, moral identity is conceptualized as a goal of moral action. Individuals want to maintain their moral identity, which in turn motivates them to act morally. Yet, moral identity motivation is not uniform. In line with SDT, it is possible to differentiate between more or less external and internal forms of moral identity motivation. The exact link between moral identity and moral action depends on the type of moral identity motivation involved. Development of moral identity trends towards more internal forms of moral identity motivation, which renders development an influential factor in shaping individuals' motivation to act morally.