Categorizing race and ethnicity for twenty-first-century statistics and economics. The increasing racial and ethnic diversity of the US population raises the question of whether the race and ethnicity categories and definitions used by federal statistical agencies to create demographic statistics on which government officials, business decision-makers, and private citizens rely fully reflect the changing population. Official definitions of existing race and ethnic groups do not always command wide agreement, and over time, some definitions that were once widely accepted may become less so based on political, legal, and social factors. Comparable measures of race and ethnicity over time are needed to accurately track historical changes in economic and social outcomes, as well as racial and ethnic segregation. This volume explores the production of economic statistics that accurately depict the complex racial and ethnic diversity of the US population in the twenty-first century. The chapters examine the consequences for economic analyses of different measurement choices concerning race and ethnicity, assess the likely implications of the 2024 changes in federal race and ethnicity measurement standards, introduce new data sets with richer demographic information, and compare measures of race and ethnicity in administrative versus survey data. They also apply existing data in creative ways to develop alternative characterizations of the changing US workforce and to illuminate important policy questions related to criminal justice, immigration, labor market discrimination, the social safety net, health care, and child welfare.