American Indian students have long registered significantly lower academic performance than their White counterparts. The primary theoretical explanation for this differential that has guided research for many decades is the cultural discontinuity thesis. Drawing on a diverse literature, we propose an alternative to this conventional wisdom in which we emphasize the role of perceived structural barriers to mobility within the stratification system. We test both of these hypotheses on a sample of 352 American Indian and more than 1,000 White high school students who participated in a 1991 survey in selected Oklahoma public schools. Our findings show that perceived structural constraints play a significant role in reducing academic performance among American Indian students. Consequently, we argue that the impact of cultural discontinuities has likely diminished over time, whereas the impact of perceived structural barriers has likely increased—a development which seems to parallel Wilson's (1978) “declining significance of race” thesis regarding Black Americans. Directions for further study are suggested.