In his landmark work, Richard Alba predicted that white ethnicity would fade into its twilight in the twenty-first century. Where direct inquiries into American white ethnicity have been scant since the millennium’s turn, the authors use recently collected (2014), nationally representative survey data to systematically assess “postmillennial” white ethnic identification. In particular, the authors explore the prevalence of whites identifying with ethnicity today, how this compares with other groups, and how drivers of white ethnic affiliation may have shifted in recent years. The data show that all ethnic claims have declined in the twenty-first-century United States, but the retreat from ethnicity has been accelerated among whites. By the authors’ estimates, only 8.4 percent of whites still claim ethnicity. The authors also find that white ethnic affiliation is now most substantively driven by racial ideology, experience, and perceived victimhood, though some demographic markers remain important. Further analyses show that remaining American white ethnic claimants now perceive white cultural advantages while simultaneously seeing themselves as victims of racial discrimination at rates that rival reports of nonwhites. In sum, these data suggest that white ethnicity has declined but not disappeared as a socially intelligible boundary claim in the postmillennial era and that it has developed as a racialized expression that holds implications for understandings of contemporary white identities, racisms, and resentments.