The paper critiques two recent suggestions, by Lei Zhong and Thomas Kroedel, about how to apply the interventionist theory of causation to cases where supervenient properties, particularly mental properties, are involved. According to both suggestions, we should hold variables corresponding to supervenient properties fixed when intervening on the subvenient properties with respect to a putative effect variable and vice versa. The paper argues that both suggestions are problematic. Zhong’s suggestion ultimately requires ad hoc exemptions from the holding-fixed requirement. Kroedel’s suggestion (...) entails severe constraints on the construction of causal models. Overall, retaining the holding-fixed requirements of interventionism for cases of supervenient properties comes at a significant price. (shrink)