It has often been noted that many of our intuitive assessments of particular actions suggest that there is an asymmetry between blameworthy and praiseworthy actions with regard to the question of whether moral responsibility requires that the agent could have acted otherwise. It is a quite different question, though, whether such an asymmetry between good and bad cases can be supported by more systematic considerations. In this paper, I will develop a new argument for a restricted version of the asymmetry, by showing that in cases of praiseworthy actions responsibility cannot generally presuppose that the agent could have acted otherwise. This argument will be based on a distinction between two different kinds of roles that moral norms can play in determining whether an action is right and in guiding our deliberation. That agents can sometimes be responsible for their praiseworthy actions even though they cannot act otherwise is best seen as a reflection of the fact that moral norms can prohibit treating certain courses of action as genuine options at all.