Over the past 25 years, AIDS has imposed a huge cost, in economic and social terms, on many countries, communities, and households around the world. At the same time, the price tag to respond fully and effectively in the areas of prevention, care and treatment, mitigation, and research has grown to tens of billions of dollars, and is continuing to increase. There have been dramatic increases in funding, but available resources are now becoming increasingly tight as the global recession adversely impacts both donor and developing countries, and as other competing priorities (e.g.