What is moral character, and how does it unfold over time? This book offers a fresh Kantian alternative to the dominant Aristotelian paradigm, which defines character as a stable set of virtues and vices. Drawing on Kant's moral philosophy, A Kantian Theory of Moral Character reframes character as a first-person commitment to moral principles - not a fixed trait, but a freely chosen, evolving practical orientation that shapes and is shaped by an agent's life as a whole. Central to this view is Kant's notion of Gesinnung: a person's fundamental moral disposition, constituted through free choice and the continuous reaffirmation of moral commitment. Bridging contemporary debates in ethics with historical insights from Kant, this study offers a compelling account of how freedom, moral commitment, temporality, and moral identity intertwine. It will interest scholars and students of philosophy, ethics, and moral psychology seeking a deeper understanding of character and moral agency.