The realization relation that allegedly holds between mental and physical properties plays a crucial role for so-called 'non-reductive physicalism' because it is supposed to secure both the ontological autonomy of mental properties and their ability to make a causal difference to the course of the causally closed physical world. For a long time however, the nature of the realization relation has largely been ignored in the philosophy of mind. It has only been a couple of years since accounts were proposed (...) according to which realization is understood against the background of the so-called 'causal theory of properties'. At least partially, the hope was to solve the problem of mental causation, in particular the kind of causal exclusion reasoning made famous by Jaegwon Kim, in a way acceptable to non-reductive physicalists. The paper asks whether a proper explication of the realization relation can indeed help explain how physically realized mental properties can be causally efficacious in the causally closed physical world and argues for a negative answer. (shrink)