Scholars often treat immigrants from the same country as a monolithic group, but intranational ethnicity is usually associated with distinctive premigration backgrounds and migration experiences and plays a role in shaping immigrant adjustment and incorporation in the host country. The authors use census data to distinguish ethnic Chinese from the Vietnamese national group to analyze educational heterogeneity across immigration generations. The results show that first-generation Chinese Vietnamese exhibit much lower levels of education than their Vietnamese counterparts, but this disparity vanishes by the 1.5 generation. The authors also find that both Vietnamese subgroups contribute to the second-generation convergence with Chinese Americans, but Chinese Vietnamese are able to overcome disadvantages more quickly and have slightly higher educational achievement than ethnic Vietnamese. Our case study illustrates how ethnicity and national origin can be disaggregated using nationally representative data and how this approach can provide unique insights into immigration studies in general.