Linguists and language activists find it difficult to win public support for preserving linguistic diversity and revitalizing endangered languages. Many remain unconvinced by the reasons linguists typically offer for valuing language diversity. One set of arguments focuses on the potential loss of traditional ecological knowledge and cultural heritage encoded in language, while another invokes a rights-based discourse, often anchored in a distributive and social justice framework. Although all of these have an important role to play, the economic significance and consequences of the global loss of linguistic diversity have not yet been seriously studied or appreciated. I will argue that a convincing case for supporting linguistic diversity may be made not on the basis of political arguments of appeal to human or minority rights, but rather on the basis of economic welfare theory, by taking account of some specific features of diverse linguistic environments as a valuable commodity. Specifically, I will show why the health of a language depends on the health of its speakers, which in turn depends on the health of the natural environment.