The economics of language is an interdisciplinary field of investigation which explores the mutual effect of language-related and economic variables. This paper reviews the main orientations and results of research, and then critically assesses the nature of standard assumptions made in the economics of language. It is shown that many of these assumptions can be expanded or adapted in order to increase the scope of relevant causal links that can be encompassed in modelling. This, in turn, requires a stronger emphasis on interdisciplinarity, in which economics has an essential role to play, in particular for selecting and designing language policy.