In this paper I shall do three things. Firstly, I shall distinguish between three senses of “imagine”: one in which (the context makes clear that) the word is used to report the occurrence of mental imagery; a second in which “imagined” is used as substantially equivalent to “thought”; and a third in which “imagine” is used as substantially equivalent to “suppose.” (And I shall argue that in neither of the two latter senses does imagining necessarily involve imagery.) Secondly, I shall discuss Hume's thesis about imagination: both because, although this is set out as a plausible (but mistaken) generalization about psychology, it nevertheless seems to me that Hume dealt with a central philosophical problem concerning imagination—the relation of descriptions to imagery—in a way that is suggestive and fruitful; and—the main reason for mentioning Hume—because a study of the relation between imagining (when this is imaging) and imagining (when this is supposing) will help us to reinterpret his thesis from a mistaken one about psychology into a correct one about logic and language. Thirdly, I shall give thecentral arguments and the conclusion of the chapter on Imagination in The Concept of Mind, and comment on them.