What must linguistic knowledge be like if it is to figure in the description and explanation of the various phenomena pre-theoretically classified as linguistic? All linguists and philosophers of language presuppose some answer to this critical question, but all too often the presupposition is tacit. In this collection of sixteen previously unpublished essays, a distinguished international line-up of philosophers and linguists address a variety of interconnected themes concerning our knowledge of language:KNOWLEDGE IN LINGUISTICS: Noam Chomsky's claim that ordinary speakers possess complex structures of linguistic knowledge was a trigger for the cognitive revolution nearly fifty years ago. This and an associated claim, that linguistics is essentially in the business of rendering such knowledge explicit, have been the target of an evolving series of sceptical objections ever since.UNDERSTANDING: Is linguistic understanding a special kind of semantic knowledge? If so, what kind? Topics covered include the viability of recent attempts to fuse Chomsky's cognitivism with Davidson's truth-theoretic approach to interpretation; the merging of linguistic and non-linguistic meaning in non-sentential speech; linguistic understanding as a kind of perception; and the objectivity of semantic knowledge.LINGUISTIC EXTERNALISM: Some regard externalist intuitions about reference as a vital contribution to our understanding of language, mind, and metaphysics; others see them as a curious but relatively unimportant component of folk linguistics, where the folk are late-twentieth-century analytic philosophers. So just what is the relation between externalist intuitions and our grasp of language?EPISTEMOLOGY THROUGH LANGUAGE: The linguistic turn in philosophy may have come full circle, but advances in epistemology and other areas of philosophy can still take the form of a better appreciation of language and our relation to it.