An estimated forty million people carry the human immunodeficiency virus (HIV), and five million more become newly infected annually. In recent years, many HIV-infected patients in wealthy nations have enjoyed significantly longer, good-quality lives as a result of antiretroviral therapy (ART). However, most infected individuals live in the poorest regions of the world, where ART is virtually nonexistent. The consequent death toll in these regions - especially sub-Saharan Africa - is begetting economic and social collapse. To inform the multiple efforts underway to deploy antiretroviral drugs in resource-poor settings, the Institute of Medicine committee was asked to conduct an independent review and assessment of rapid scale-up ART programs. It was also asked to identify the components of effective implementation programs. At the heart of the committee's report lie five imperatives: immediately introduce and scale up ART programs in resource-poor settings; devise strategies to ensure high levels of patient adherence to complicated treatment regimens; rapidly address human-resource shortages to avoid the failure of program implementation; continuously monitor and evaluate the programs to form the most effective guidelines and treatment regimens for each population; and prepare to sustain ART for decades.