This chapter conceptualizes the field of linguistic anthropology in terms of one general criterion: ontological commitment. Linguistic anthropologists share some core ideas about a small set of essential properties of language, all of which are centered upon one basic assumption that language is a non-neutral medium. The ways in which this basic assumption has been interpreted and transformed into particular research projects gives linguistic anthropology its unique identity within the social sciences and the humanities. The chapter focuses on three essential properties of language that are assumed by linguistic anthropologists: language is a code for representing experience, language is a form of social organization, and language is a system of differentiation. Boas' discussion of the influence of language on the ability of an individual to hear subtle differences in the sounds of another language is the explicit statement of the ontological commitment to thinking of language as a non-neutral medium.