The association of passion with desire has a long history, from Aristotle to contemporary philosophers. The Aristotelian conception of passion as involving desire has exerted a considerable influence on modern philosophers. I shall take this idea to be the thesis that emotion implies desire. In order to elaborate this thesis, in this paper, I shall focus on Hume’s theory of passion in Book 2 of Treatise. To this end, I first of all present an interpretation of Hume that relies on an account of desire as such that I have developed. Secondly, I demonstrate what kinds of authority, if any, desires have in Hume’s view of the explanation of action.