Recent immigrant assimilation literature has highlighted the tremendous heterogeneity that exists within foreign-born and U.S.-born second generation populations—and thus, the importance of a broader generational cohort framework that encompasses nativity, immigrant generation, age at arrival, and parental nativity. Using data from the 2003 California Health Interview Survey, this paper examines generational cohort differences in access to health services among Asian and Latino immigrant adults. Results showed that immigrants arriving in the U.S. as children had better access to services, one exception being middle-aged and older Asians. Individuals arriving in the U.S. as adults were significantly less likely than the third-and-later generation to have a usual source of care, and also had fewer physician visits. Across all cohorts, Latinos fared worse than both Asians and Whites. This study highlights the value of a generational cohort framework—specifically, the importance of age at arrival—in examining health access among immigrants.