Ignorance is often a perfectly good excuse. There are interesting debates about whether non-culpable factual ignorance and mistake subvert obligation, but little disagreement about whether non-culpable factual ignorance and mistake exculpate. What about agents who have all the relevant facts in view but fail to meet their obligations because they do not have the right moral beliefs? If their ignorance of their obligations derives from mistaken moral beliefs or from ignorance of the moral significance of the facts they have in view, should they be excused for failing to meet their moral obligations? It is not obvious that they should. In this paper we argue that the best non-skeptical accounts of moral responsibility acknowledge that factual ignorance and mistake will diminish moral responsibility in a way that moral ignorance and mistake will not. That is because factual ignorance is often non-culpable so long as it meets certain merely procedural epistemic standards but the same is not true of moral ignorance. Our argument is that the assumption that it is gets the standards of culpability for moral ignorance wrong, and that the mistake is encouraged by the thought that culpability in general requires an instance of known wrongdoing: that acting wrongly requires de dicto unresponsiveness to one’s obligations at some stage. We deny this and conclude that, therefore, ignorance and mistaken belief are indeed often perfectly good excuses – but far less often than some philosophers claim.