In this dissertation I analyze the social history of an anthropological collection at the Smithsonian Institution (SI). Combining archival and historical research with interviews, I trace the Army Medical Museum (AMM) collection from its origin in the mid-nineteenth century to the present. The Smithsonian's AMM collection is the product of mid- to late-nineteenth century government science. Assembled in the midst of westward expansion and colonization, this collection is the result of numerous government-sanctioned collecting efforts. Accordingly, the objects and human remains that comprise this collection were taken from scores of Native American tribes from all parts of the United States. Amassed during some of the darkest moments in the history of the United States---marked by warfare, death and the displacement of countless Native Americans---the AMM collection represents the Smithsonian's earliest collecting efforts. The social history of this collection spans from the earliest days of the SI to the present, marked by concerns regarding cultural property rights. And what the present moment demonstrates is the continued relevance of this colonial past, especially in the context of repatriation. I analyze critical contemporary issues of repatriation in terms of the historical legacy of collecting in the U.S. and demonstrate the role that collections play in negotiating identities. For that purpose, I begin with the supposition that objects shape as well as materialize identity, and that disciplines define themselves by virtue of what they collect. I examine recent shifts in what is deemed ethically appropriate for collection and how this affects the various ways museum anthropologists define the discipline. Ultimately, this dissertation advances a critical historical analysis of the AMM collection, providing a more dynamic understanding of the role that repatriation plays in redefining the roles of anthropologists within museums.