Approximately 20% of the estimated 1.2 million persons living with human immunodeficiency virus (HIV) infection in the United States at the end of 2008 were not aware of their infection. Testing, diagnosis, medical care, treatment with highly active antiretroviral therapy (HAART), and access to prevention services soon after HIV infection can prevent morbidity and mortality and reduce a person's risk for transmitting HIV. In 2006, CDC recommended screening patients aged 13--64 years for HIV infection in health-care settings that have a prevalence of undiagnosed HIV infection of ≥0.1%. In October 2007, CDC initiated the Expanded HIV Testing Initiative (ETI), through which it funded 25 health departments to facilitate HIV screening and increase diagnoses of HIV infections and linkage to care among populations disproportionately affected by HIV, especially non-Hispanic blacks. This report describes the results of that effort. Annual progress reports designed to provide data specific to ETI indicated that 2,786,739 HIV tests were conducted, of which 29,503 (1.1%) were positive and 18,432 (0.7%) resulted in new HIV diagnoses. Blacks accounted for 1,411,780 (60%) of tests and 11,638 (70%) of new HIV diagnoses. Clinical settings comprised at least 75% of the 1,331 testing venues and accounted for 90% of all tests and 81% of all new HIV diagnoses. Based on follow-up data available for 16,885 persons with new HIV diagnoses, 12,711 (75.3%) were linked successfully to HIV primary care. Through expanded HIV testing activities, substantial numbers of persons previously unaware of their HIV infection were identified and linked to care. Health departments should continue to partner with clinical-care providers to provide routine HIV screening, especially in populations disproportionately affected by HIV.