In this paper, I show how a novel treatment of speech acts can be combined with a well-known liberal argument for multiculturalism in a way that will justify claims about the preservation, protection, or accommodation of minority languages. The key to the paper is the claim that every language makes a distinctive range of speech acts possible, acts that cannot be realized by means of any other language. As a result, when a language disappears, so does a class of speech acts. If we accept that our social identities are in large part constituted by the decisions we make about how to speak, then language loss will amount to a substantial infringement on our autonomy in a particularly important domain.