Instances of many supervenient properties have physical effects. In particular, instances of mental properties have physical effects if non-reductive physicalism is true. This follows by a straightforward argument that assumes a counterfactual criterion for causation. The paper presents that argument and discusses several issues that arise from it. In particular, the paper addresses the worry that the argument shows too many supervenient property-instances to have physical effects. The argument is also compared to a similar argument that has been suggested by Lei Zhong and is shown to be superior to the latter.