This essay proposes a new interpretation of Clauberg’s account of the mind-body problem, against both occasionalist and interactionist readings. It examines his treatment of the mind-body relation through the lens of his theories of substance and cause. It argues that, whereas Clauberg embraces Descartes’s substance dualism, he retains a broadly scholastic theory of causation as the action of essential powers. On this account, mind and body are distinct, power-bearing substances, and each is a genuine secondary cause of its own modifications. Between mental and bodily modes, however, there is only a special, divinely instituted correlation, but no causation. Clauberg’s view has the consequence that the conjunction of mind and body cannot be understood causally but only as the covariation of sensations and brain states, which he treats as mutually referring signs.