In Aristotle’s Vice, I aim to reconcile Aristotle’s claims that the vicious are ignorant of the good, motivated to do what they believe to be best, and unlikely to improve with Aristotle’s claims that the vicious person is also responsible for her character and fundamentally miserable. In order to make sense of these five claims it is important to distinguish the vicious character (κακία) from the incontinent (ἀκρασία) and brutish (θηριότης) characters, while distinguishing these three from vices that are merely characteristics (but not ἕξεις). Only when these distinctions are honored consistently can one see how the above claims are compatible. In addition, a degree-based account of the nature of moral knowledge and moral ignorance is key to understanding all morally inferior states and conditions. In conclusion, I argue that, for Aristotle, moral agency is satisfied by a minimal degree of moral knowledge, which is not immune to revision. The vicious previously had such knowledge, but their acquired ignorance prevents them from recognizing this fact, and this (among other things) makes them perpetually miserable.