This article offers an account of Kant's conception of the duty of self-love, a rarely researched subject, by investigating how he appropriated Alexander Gottlieb Baumgarten's prior conception. I argue that exploring this appropriation helps us to gain new insights into Kant's conception of duty, a leading thread in Kant's ethics. Substantiating this argument, I derive the following conclusions. First, Kant peculiarly affirms a duty to rational self-love of delight. To be more precise, human beings ought rationally to love themselves in (...) such a way that they are content with—or have a positive feeling about—themselves in acting on maxims that they are pleased to see submitted to the moral law. Further, rational self-love of delight results from declining pathological forms of self-love. Second, Kant retains, to a meaningful extent, Baumgarten's conception of the duty to self-love where feeling and rationality achieve their distinct elevation. (shrink)