“Duty” plays a twofold role in Kant’s explication and explanation of moral obligation. One the one hand Kant believes that human beings, because of our dual nature as both rational and sensuous creatures, experience the requirements of practical reason as constraints, as duty. On the other hand Kant also uses the term “duty” to describe the underlying normative structure of (pure) practical reason, which makes possible, explains and justifies the cogency of this experience. In my talk I will discuss how these two aspects of Kant’s conception of duty are related and highlight (some of) the tensions, which his dual view of moral obligation gives rise to.