Despite the importance of education for shaping individuals' life chances, little research has examined trends and differences in educational attainment for detailed demographic subpopulations in the United States. We use labor market segmentation and cohort replacement theories, linear regression methods, and data from the National Health Interview Survey to understand educational attainment by race/ethnicity, nativity, birth cohort, and sex between 1989 and 2005 in the United States. There have been significant changes in educational attainment over time. In support of the cohort replacement theory, we find that across cohorts, females have enjoyed greater gains in education than men, and for some race/ethnic groups, recent cohorts of women average more years of education than comparable men. And in support of labor market segmentation theories, foreign-born Mexican Americans continue to possess relatively low levels of educational attainment. Our results can aid policymakers in identifying vulnerable populations, and form the base from which to better understand changing disparities in education.