Kant's aim in Section III of the Groundwork is to establish the supreme principle of morality. To accomplish his aim he finds it necessary to present a justification of freedom. Commentators generally regard Kant's overall argument as a failure, because they regard his justification of freedom as a failure. In this paper I shall present three arguments. First, I shall argue that commentators, for the most part, look to the wrong text for Kant's Groundwork justification of freedom. They look to (...) pars. 10–16 for an argument for freedom, but the collection of propositions, which Kant presents there, is aimed at showing something other than freedom. Second, I shall argue that to the extent that they look to the correct text, namely, par. 4, they misinterpret Kant. Third, I shall set out and evaluate the actual justification of freedom which Kant presents in par. 4. (shrink)