Worries about mental causation are prominent in contemporary discussions of the mind and human agency. Originally, the problem of mental causation was that of understanding how a mental substance (thought to be immaterial) could interact with a material substance, a body. Most philosophers nowadays repudiate immaterial minds, but the problem of mental causation has not gone away. Instead, focus has shifted to mental properties. How could mental properties be causally relevant to bodily behavior? How could something mental qua mental cause (...) what it does? After looking at the traditional Problem of Interaction, we survey various versions of the property-based problem and look at proposed solutions to them. (shrink)