Dualism holds that some mental events are fundamental and non-physical. I develop a prima facie plausible causal argument for dualism. The argument has several significant implications. First, it constitutes a new way of arguing for dualism. Second, it provides dualists with a parity response to causal arguments for physicalism. Third, it transforms the dialectical role of epiphenomenalism. Fourth, it refutes the view that causal considerations prima facie support physicalism but not dualism. After developing the causal argument for dualism and drawing out these implications, I subject the argument to a battery of objections. Some prompt revisions to the argument. Others reveal limitations in scope. It falls out of the discussion that the causal argument for dualism is best used against physicalism as a keystone in a divide and conquer strategy.