Tuberculosis in the United States is primarily and increasingly a disease of minorities and the foreign-born. Tuberculosis among non-Hispanic whites is predominantly a disease of the elderly, whereas among minorities and the foreign-born, it is primarily concentrated in young adults. In the past few years, tuberculosis has increased among young adults, especially those who are black or Hispanic. Available data support the hypothesis that the spread of human immunodeficiency virus infection has increased the risk of tuberculosis. A substantial proportion of tuberculosis in the United States is potentially preventable through the administration of preventive therapy to high-risk populations.