Normative realists might be assumed to have few worries about semantics. After all, a realist might initially hope to simply adopt the best semantic theory about ordinary descriptive language. However, beginning with the non-cognitivist appropriation of the open question argument, a number of philosophers have posed serious objections to the realist’s ability to offer a plausible semantic theory. This paper introduces the two most influential semantic challenges to normative realism: the open question argument, and the Moral Twin Earth argument. It explains the major replies to these challenges offered by realists, and locates these challenges within the broader debate over what sort of semantic theories might be plausible candidates for a normative realist to adopt.