Researchers in the psychological sciences have put forward the thesis that various sources of psychological, cognitive, and neuroscientific evidence demonstrate that being conscious of our mental states does not make any difference to our behaviour. In this paper, I argue that the evidence marshalled in support of this view — which I call psychological epiphenomenalism — is subject to major objections, relies on a superficial reading of the relevant literature, and fails to engage with the more precise ways in which (...) philosophers understand mental states to be conscious. I then appeal to work on implementation intentions to demonstrate that an intention's being 'access conscious' enhances its functional role, which makes it more likely that we will successfully carry out our intended behaviour. The result is that consciousness in at least one relevant sense is not epiphenomenal, with further work remaining to be done to show how other kinds of consciousness cause behaviour too. (shrink)