The ‘Introduction’ to Naturrecht Feyerabend is the transcript of a lecture Kant held at the very time he began writing the Groundwork. It contains the first securely dated occurrence of the term ‘autonomy’ (and its first occurrence in the context of moral philosophy) in Kant’s work. It argues that moral imperatives are categorical and asks how they are possible. Kant’s attempts to answer this question circle around the idea that freedom must be ‘a law to itself’ and lead him to the claim that the form of universal lawfulness, independently of any inclination, can determine the will. Thus various central elements of the Groundwork conception of autonomy are already present in this text. Other elements, most notably the universal law formulation of the categorical imperative and the emphasis on reason as both source and addressee of moral commands, are conspicuously absent. Following a reconstruction of Kant’s overall argument for autonomy of the will in the notes, the paper offers a detailed interpretation of central passages concerning autonomy in order to identify both similarities and differences between the conceptions of autonomy in the ‘Introduction’ and in the Groundwork.