Kant’s main concern in his famous essay on enlightenment is the relation between enlightenment and the political order. His account of this relation turns on the idea of the freedom of public reason. This paper develops a new interpretation of Kant’s concept of public reason. First, it argues that Kant conceives of public reasoning as a matter of speaking in one’s own name to the commonwealth of the public. Second, it draws on Kant’s republican conception of freedom in order to develop an account of the grounds of the freedom of public reason. It argues that the state’s duty with respect to public reason is an aspect of its duty to protect the independence of citizens. Contrary to what is commonly thought, this duty is not an obligation to refrain from interfering in the sphere of public reason. The state may have a positive, though limited, role to play in enlightenment.