This paper examines the controversy that followed the 1987 publication of Joseph Greenberg's book, Language in the Americas, attending to the role of language and linguistic research within overlapping disciplinary traditions. With this text, Greenberg presented a macro‐level tripartite classification that opposed then dominant fine‐grained analyses recognizing anywhere from 150 to 200 distinct language families. His proposal was the subject of a landmark conference, examining strengths and weaknesses, the unpublished proceedings of which are presented here for the first time. For (...) specialists in the anthropological and comparative‐historical study of Indigenous American languages, Greenberg's intervention highlighted the tension between language, conceived as an abstract object of study, and languages, understood to be carriers of specific cultural knowledge. For physical anthropologists and archaeologists, his theory was initially fortuitous on programmatic, substantive, and methodological grounds. The essay will show how interdisciplinary appeals were figured by supporters as a virtue, and by critics as a vice. The essay further highlights ethical reasons for integrating historical narratives of science and the humanities. (shrink)