The paper discusses Linda Zagzebski's account of epistemic authority. Building on Joseph Raz's account of political authority, Zagzebski argues that the basic contours of epistemic authority match those Raz ascribes to political authority. This, it is argued, is a mistake. Zagzebski is correct in identifying the pre-emptive nature of reasons provided by an authority as central to our understanding of epistemic authority. However, Zagzebski ignores important differences between practical and epistemic authority. As a result, her attempt to explain the rationality of belief on authority by applying an analogue of Raz's Normal Justification Thesis to the domain of belief fails. A successful explanation of the rationality of belief on authority...