In this chapter, we attempt to unmask the ideological bias inherent in influential conceptions of the methods, motivations and practices of endangered language documentation research (ELDR) by addressing the unequal exchange that frequently characterizes the relationship between the linguistic researcher, on the one hand, and the language community and, in some cases, local researchers, on the other. We highlight the extent to which common answers to the question “Why document endangered languages?” suppress the sociocultural and historical relations within which ELDR practices are situated. We review the historical evolution of the conceptualization of language documentation research, and its relationship to language preservation and revitalization. We ask what it is that makes ELDR scientific, critically analysing the models of “language” and of “science” that are frequently deployed in arguments for its importance, and question the value-neutrality of the notion “scientific community” in this context. We suggest that the conjunction of dominant concepts of “language” and “data”, and the relations between “international” and “local” ELD researchers, generates an ideological construction of unequal competence that operates to justify unequal North-South exchange relations. We document this claim of unequal and at times abusive North-South exchange with brief, anonymized case studies. We conclude by noting that, in comparison with other social science disciplines, linguistics seems resistant to reflexive and self-critical analysis of its ideological dimension; and suggesting possible ways of raising awareness and generalizing models of good practice.