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