This paper offers an imminent interpretation of Kant's political teleology in the context of his response to Moses Mendelssohn in Theory and Practice III concerning prospects of humankind's moral progress. The paper assesses the nature of Kant's response against his mature political philosophy in the Doctrine of Right. In `Theory and Practice III' Kant's response to Mendelssohn remains incomplete: whilst insisting that individuals have a duty to contribute towards humankind's moral progress, Kant has no conclusive answer as to how individuals might act on that duty. `Theory and Practice III' lacks a clear conception of the distinctness of political morality from the domain of virtue; Kant's resort to teleological argumentation is indicative of his lack of an account of instituting Right. The latter can be found in the Doctrine of Right—yet Kant's earlier teleological arguments contribute crucially to the development of his mature morality of Right.