In his influential discussion of thick concepts Williams argues that the facts that make judgements, which apply thick concepts correctly, true, provide reasons for action — albeit only for the members of a community who have a disposition to be guided by the concepts in question. His internalism about practical reasons may help to explain this claim: the disposition to be guided by a thick concept provides the link to existing motives that all reasons must have. Understood thus, Williams makes room for explaining and vindicating Oscar Wilde's ‘…not one of my words’-dictum about certain thick concepts. However, the chapter argues that the combination of the account of thick concepts that Williams expounds with reasons internalism leads into a dilemma: either the facts that thick concepts, correctly applied, refer to, do not provide reasons (not even for those who have a disposition to be guided by them) — except perhaps in the way in which any other, non-evaluative fact may provide a reason; or they provide reasons for everyone, independently of the disposition to be guided by the concepts. Getting out of the dilemma requires giving up on reasons internalism or, alternatively, modifying the account of thick concepts that Williams sets out.