What is meaning? Paul Horwich presents an original philosophical theory, demonstrates its fruitfulness, and defends it against all comers. At the core of his theory is the idea, made famous by Wittgenstein, that the meaning of a word derives from its use; Horwich articulates this idea in a new way that will restore it to the prominence that it deserves. He surveys the diversity of valuable insights into meaning that have been gained in the twentieth century, and seeks to accommodate them within his theory. His aim is not to correct a common-sense view of meaning, but to vindicate it: he seeks to take the mystery out of meaning.