On the standard picture of Kant’s moral theory and the place of psychology within it, most of our subjective, psychological conditions (such as our instincts, feelings and desires) are obstacles to morality, and only some are aids. However, even the latter are mere instruments in the performance of moral actions on the basis of our adopted maxims (our own principles of acting). This picture therefore seems to leave no room for a truly relevant moral psychology. In this dissertation, I primarily aim to show that Kant’s moral theory contains a moral psychology, the relevance of which lies in the fact that Kant took certain psychological conditions to be necessary not only for observing moral maxims but also for adopting them in the first place. To explain why development of those conditions is needed if we are to adopt moral maxims of virtue on which we actually act, I first turn to Kant’s notion of moral self-control. I then discuss the strength and weakness of our capacity for self-control. Finally, I interpret Kant’s conception of conscience and expand on this interpretation while developing a theoretical framework for examining whether the moral flaws characteristic of individuals with psychopathy are traceable to their dysfunctional consciences. By demonstrating the fruitfulness of Kant’s theory of conscience when it comes to explaining the moral incompetence of psychopaths, I show that Kant’s moral psychology is relevant to contemporary moral psychology.