This article examines Kant’s theory of property through a comparative analysis of Gottfried Achenwall’s justification of ownership rights. I argue that at the core of Achenwall’s and Kant’s understanding of ownership rights lies the idea that rights are to be acquired through a juridical act (factum iuridicum, rechtlichen Act) of the will. However, while Achenwall thinks of this act as emerging from a private will, Kant holds that rights and obligations can only be brought about by an act of the general will. By contrasting these two views, I aim to illuminate one of the main features of Kant’s theory of property, namely, that ownership rights are only possible in a rightfully constituted state. I conclude with a suggestion regarding Kant’s view of the notion of ‘provisional’ possession in the state of nature.