A central concern in Hume scholarship is that of the relationship between Hume's early <em>Treatise of Human Nature</em> and his later <em>Enquiry Concerning Human Understanding</em>. Is the <em>Enquiry</em> merely a simplified restatement of the contents of Book 1 of the <em>Treatise</em>, or do the two substantially differ? Another vital issue is as follows: how can we reconcile Hume's seemingly destructive skepticism with his constructive, naturalistic program for a science of human nature? Hsueh M. Qu provides here a new interpretation of Hume's epistemology, addressing these perennial and central questions of Hume scholarship, and showing them as intimately related. He argues that the <em>Enquiry</em> indeed differs from the <em>Treatise</em> because Hume changes his response to skepticism between the two works. With this understanding, Qu clarifies a host of enduring questions about the works. Because the <em>Treatise</em> has as its primary focus the psychological naturalistic project, its treatment of epistemological issues is helter-skelter, arising unsystematically from the results of the central psychological investigation. Consequently, Hume finds himself forced into a response to skepticism founded on the Title Principle. However, this response is deeply problematic, as Hume himself seems to recognize. In contrast to the <em>Treatise</em>, the <em>Enquiry</em> emphasizes the epistemological aspects of Hume's project, and offers a radically different and more sophisticated epistemology that takes the form of an internalist reliabilism. <em>Hume's Epistemological Evolution</em> establishes the <em>Enquiry</em> as far more than a watered-down version of the <em>Treatise</em>, and as a worthy object of philosophical study in its own right. Qu offers a broader, master narrative encompassing both the <em>Treatise</em> and the <em>Enquiry</em> that stakes out a narrative of evolution across the two works--a narrative that explains some of the most central interpretive questions in Hume scholarship.