What is it that makes a mental state conscious? Recent commentators have proposed that for Kant, consciousness results from differentiation: A mental state is conscious insofar as it is distinguished, by means of our conceptual capacities, from other states and/or things. I argue instead that Kant’s conception of state consciousness is sensory: A mental state is conscious insofar as it is accompanied by an inner sensation. Interpreting state consciousness as inner sensation reveals an underappreciated influence of Crusius on Kant’s view, (...) solves some long-standing puzzles concerning Kant’s difficult doctrine of self-affection, and sheds light on his theory of inner experience. (shrink)