Abstract: It’s not uncommon in contemporary philosophical work on desire, emotions, intentional action, rational attitudes and the like to speak of a distinctive form of ‘intelligibility’ that characterises instances of these phenomena, at least when things are going as they should. Often this is contrasted with a correlative form of ‘unintelligibility’ that may be on display when things go as they shouldn’t. Usually some bit of philosophical theory then comes in to explain what makes the difference, and the intelligible–unintelligible contrast is thus used to support the relevant bit of theory. This paper raises some questions about the philosophical uses of ‘intelligibility’ and makes a start at addressing them. I distinguish two different ways of drawing an intelligible–unintelligible contrast, corresponding to (something like) two senses of ‘intelligible’. This raises a question as to whether arguments of the sort just described might be equivocating, at least in some cases. I end by discussing one way in which the two senses of intelligibility could be connected in the specific case of intentional action, and raise some doubts about the extent to which this connection will generalise.