Jaegwon Kim argues that if mental properties are irreducible with respect to physical properties then mental properties are epiphenomenal. I believe this conditional is false and argue that mental properties, along with their physical counterparts, may overdetermine their effects. Kim contends, however, that embracing overdetermination in the mental case, due to supervenience, renders the attribution of overdetermination vacuous. This way of blocking the overdetermination option, however, makes the attribution of mental epiphenomenalism equally vacuous. Furthermore, according to Kim’s own logic, physical properties, and not mental properties, may be in danger of losing their causal relevance.