Abstract: Research shows that the institutionalization of legitimacy criteria has created contested meanings of being indigenous to the United States, which leads to an unrelenting debate about authentic indigeneity among indigenous people and between indigenous communities. While instituted through colonizing federal Indian policy, the “real Indian” trope is now a social fact for American Indians. Thus, indigeneity claims commonly encounter resistance in the United States, even within indigenous communities. This work explores how indigeneity claims encounter opposition at interpersonal and group levels and the consequences of authenticity policing. I ask two guiding questions: What authenticity markers hold the most value for American Indians? How do American Indians justify authenticity policing? Using a qualitative approach and an indigenous epistemology, I examine the phenomenon of internalizing the real Indian trope and the impact of policing authenticity through conversations with 45 indigenous people. I find that achieving authenticity is elusive because of its dynamic nature within the local specificity of social contexts. I present and discuss two major signifiers of American Indian identity and major sites of authenticity contestation: (1) blood as protection, culture, and belonging, and (2) Indian cards as protection, responsibility, and belonging.