 The identity theory of truth was influential in the formative years of modern analytic philosophy, and has come to prominence again recently. Broadly speaking, it sees itself as a reaction against correspondence theories of truth, which maintain that truth-bearers are made true by facts. The identity theory maintains, against this, that at least some truth-bearers are not made true by, but are identical with, facts. The theory is normally applied not at the level of declarative sentences, but to what such sentences express. It is these items—or, again, some of them—that are held to be identical with facts. Identity theorists diverge over the details of this general picture, depending on what exactly they take declarative sentences to express, whether Fregean thoughts (at the level of sense), Russellian propositions (at the level of reference), or both, and depending also on how exactly facts are construed. But, to give a precise illustration, an identity theorist who thinks that declarative sentences express Russellian propositions will typically hold that true such propositions are identical with facts. The significance of the identity theory, for its supporters, is that it appears to make available the closing of a certain gap that might otherwise be thought to open up between language and world and/or between mind and world. If its supporters are right about this, the identity theory of truth potentially has profound consequences both in metaphysics and in the philosophies of mind and language.