To address what I call the “Uniformity”, “Capriciousness”, and “Reducibility” objections, recent agent-causation theories hold that agent-causation is a type of substance causation. Substance causation consists in substances producing effects by exercising or manifesting their powers. Importantly, these versions of agent-causation assume a realist metaphysics of powers, where powers are properties of substances that can exist unmanifested. However, the realist theories of powers that agent-causal theories have relied upon explicitly hold that powers—rather than their substances—are causes. Substances are merely derivative (...) causes, as the bearers of powers. Critics therefore argue that agent-causation is reducible to causation by the agent’s powers. In this paper, I argue that agent-causation is reducible to causation by the agent’s powers only if powers are self-exemplifying properties. I also offer reasons for why powers—especially agent-causal powers—are non-self-exemplifying properties, in support of the irreducibility of agent-causation. (shrink)