Many studies, but not all, suggest that immigrant health worsens with duration of residence in the United States. Cohort effects may explain the inconsistent findings; not only are cohort effects confounded with duration, but the timing of entry into the United States may also create qualitatively different migration experiences. The present study tests for duration and cohort patterns among Asian immigrants to the United States across six year-of-entry cohorts (pre-1980, 1981-85, 1986-90, 1991-95, 1996-2000, 2001-05). Data come from the Asian American sample (n = 44,002) of the 1994-2009 waves of the National Health Interview Survey. The data show cohort differences for self-rated health, such that more recent cohorts showed improved baseline health compared to older cohorts. After accounting for cohorts, there was no significant change in self-rated health by duration of residence. Older cohorts actually showed improving self-rated health with longer duration. Obesity showed the opposite pattern; there were no differences across cohorts, but duration in the United States correlated with higher obesity. These results imply that immigrant health is not simply an issue of duration and adaptation; instead, they underscore the utility of considering cohorts as broader contexts of migration. Collectively, the results encourage future research that more carefully examines the etiological mechanisms that drive immigrant health.