This article is concerned with Mark Timmons and Terence Horgan's influential twin-earth argument against the semantic views of that school of thought in metaethics that has come to be known as “Cornell realism”. The semantic views of Cornell realism have been developed in greatest detail by Richard Boyd, and it is Boyd's view that is targeted by Timmons and Horgan. In the first part of the article, the twin-earth argument is introduced and two versions of it are disentangled. Thereafter, a defensive strategy is developed against the most powerful version of the argument. The conclusion of the article is that Timmons and Horgan's argument does not succeed in showing that the semantic views associated with Cornell realism are false.