Prima facie, so-called ‘quality of will’ accounts of responsibility are better placed to deal with troublesome cases such as pure omissions. But, as I am going to argue, they face the important additional task of spelling out precisely which kind of faults or mistakes on the agent’s part make the agent the appropriate target of specifically moral blame. In this paper, I will try to fill out what I take to be an important lacuna in ‘quality of will’ approaches, by providing at least the beginning of an answer to this question. As I will argue, the most promising way to fill out this lacuna is to take up a version of what Joseph Raz has called the Rational Functioning Principle, according to which we are responsible for conduct – and omissions – if this conduct “is the result of the functioning, successful or failed, of our powers of rational agency, provided those powers were not suspended in a way affecting the action.” (2011, 231). While this account will need some further qualification, I do think it provides, in outline, the best approach to understanding responsibility in general and for pure omissions specifically. However, making good on this claim will require some argument for why our behaviour or our omissions’ being the result of a failed or deficient functioning of our rational powers is precisely what makes us morally responsible for them. The argument I will develop will be based on the idea that moral blame involves essentially judging an agent by reference to a specific set of norms which are inescapable and binding him in a characteristic way (i.e. the way which is characteristic for specifically moral norms). And the rational powers whose failed or deficient exercise was responsible for the behaviour or omission will have to be precisely those powers whose possession makes moral norms inescapable and binding for us.