In this chapter I survey the two main families of views about the moral psychology of moral responsibility, i.e., about the mental capacities or psychological functioning that distinguishes responsible agents from non-responsible agents. These are self-expression views, which maintain that responsible agency is essentially about being able to express one's practical stance or moral orientation in conduct; and reasons-responsiveness views, according to which responsible agency requires a suite of powers that make their possessors capable of detecting and responding apppropriately to the moral considerations against their conduct (in the case of wrong actions). I explore different contemporary variants of each of these families of views and assess their weaknesses and strenghts. Finally, I sketch a methodology for settling this debate, the essence of which is to note that the debate about the moral psychology of moral responsibility is ancilliary to a broader debate about the nature of moral responsibility itself and, in particular, about the nature of blame and blaming reactions. On the basis of this methodology, I end up taking sides with a particular variant of the self-expression paradigm.