In this interpretive analysis elucidating fundamental tensions of the implementation of the 2001 No Child Left Behind (NCLB) Act within Native-serving schools, we point to ways in which NCLB further limits the already contested sovereignty tribes exercise over how, and in what language their children are instructed. We discuss issues related to the self-determination exercised by schools, some problematic cultural assumptions inherent in the NCLB law, and the legal tension between NCLB and the 1990/1992 Native American Languages Act. Finally, we examine the detrimental effects that NCLB accountability measures could have on Navajo communities, and look at how the Navajo Nation has addressed sovereignty over tribal education in recent years vis-a-vis NCLB.