BACKGROUND: Although the benefits of identifying and treating asymptomatic HIV-infected individuals are firmly established, health care providers often miss opportunities to offer HIV-testing. OBJECTIVE: To evaluate whether a multi-component intervention increases the rate of HIV diagnostic testing. DESIGN: Pre- to post-quasi-experiment in 5 Veterans Health Administration facilities. Two facilities received the intervention; the other three facilities were controls. The intervention included a real-time electronic clinical reminder that encourages HIV testing, and feedback reports and a provider activation program. PATIENTS: Persons receiving health care between August 2004 and September 2006 who were at risk but had not been previously tested for HIV infection. MEASUREMENTS: Pre- to post-changes in the rates of HIV testing at the intervention and control facilities RESULTS: At the two intervention sites, the adjusted rate of testing increased from 4.8% to 10.8% and from 5.5% to 12.8% (both comparisons, p < .001). In addition, there were 15 new diagnoses of HIV in the pre-intervention year (0.46% of all tests) versus 30 new diagnoses in the post-intervention year (0.45% of all tests). No changes were observed at the control facilities. CONCLUSIONS: Use of clinical reminders and provider feedback, activation, and social marketing increased the frequency of HIV testing and the number of new HIV diagnoses. These findings support a multimodal approach toward achieving the Centers for Disease Control and Prevention's goal of having every American know their HIV status as a matter of routine clinical practice.