Section 106 of the 1966 National Historic Preservation Act (NHPA) requires that federal agencies “must take into account” the impact of their regulatory actions on historical properties, among them the “traditional cultural properties” of American Indian tribes. Conceiving of tribes' own social practices in terms of property creates the possibility for making claims about its loss for tribes, but it also problematizes their cultures' inherent dynamism that implicates its putative authenticity. This article offers commentary on the implications of practicing a form of action anthropology for the concept of culture via discovery and explication of such property under the NHPA. The context is a small American Indian community's effort to resist the development of a copper-zinc mine adjacent to its reservation, on land that holds significant meaning for the community.