Latinos have disproportionately high rates of diet-related diseases which are associated with acculturation to the U.S. This negative shift in dietary quality is paradoxical in light of gains in income and education that would be expected to lead to better diet. We examined the extent to which the dietary acculturation paradox among Mexican Americans can be explained by segmented assimilation, a theory that considers how immigrants' and their descendants' trajectories of integration are influenced by a complex interplay of individual, social, and structural factors. First, we performed confirmatory cluster analysis to identify three assimilation segments (classic, underclass, and selective) based on education, income, and an acculturation proxy derived from language, nativity, and time in the U.S. among Mexican-origin participants (N = 4475) of the 2007-2016 National Health and Nutrition Examination Survey (NHANES). These segments were then used as independent variables in linear regression models to estimate the relationship between cluster and dietary quality (assessed by the Health Eating Index (HEI)) and the interaction between cluster and gender, controlling for marital status. There were strong effects of cluster on dietary quality, consistent with hypotheses per segmented assimilation theory. The classic assimilation segment had the poorest diet, despite having higher income and education than the underclass segment. The selective segment had higher or similar dietary quality to the underclass segment. Consistent with expectations, this difference was driven by the relatively higher consumption of greens and beans and whole grains of those in the selective and underclass segments. Overall, women had better diets than men; however, the strongest gender contrast was in the underclass segment. This study advances understanding of dietary acculturation and potential disparities in diet-related health outcomes.