DescriptionLinguistic diversity abounds. Speakers do not all share the same vocabularies, and often use the same words in different ways. Moreover, language changes. These changes have particular semantic effects: the meaning of a word can change both over the course of a long period of time and over the course of a single dialogue. In Language Change in Context I develop a foundational account of linguistic meaning that is responsive to these descriptive facts concerning language variation and change. Noam Chomsky and Donald Davidson have, among others, argued that the lack of linguistic homogeneity among a community of speakers and the possibility of semantic innovation undermine standard philosophical characterizations of language as a shared system of sign-meaning pairs employed for the purposes of communication. I draw a different conclusion from the phenomena in question. I propose a dynamic characterization of the relation between agents and the languages they use for the purposes of communication. According to this dynamic account, agents regularly adapt the shared system of sign-meaning pairs that they use for the purposes of a conversation, and it is precisely this adaptive feature of language that makes it an effective instrument for successful communication. I develop my account over the course of three self-standing chapters. In Chapter One I detail the animating ideas behind my dynamic approach to language with particular attention to Chomsky’s critique of the theoretical utility of “public languages.” Chapter Two concerns the relationship between linguistic conventions and linguistic communication, with special attention given to cases of lexical innovation. Chapter 3 develops and defends semantic pluralism: the thesis that a semantic theory for a language associates a range of admissible semantic values with the simple and complex expressions of that language.