The AIDS virus appears to be present in almost every nation. Its social, economic, and political impacts are as important as the threat that it represents to public health. AIDS can be considered to be three separate and interrelated global epidemics. The first is the epidemic of AIDS virus infection. The second is the epidemic of the disease AIDS, which follows the first epidemic with a delay of several years. The third epidemic is the social, cultural, economic, and political reaction to AIDS. In response to the epidemic the World Health Organization's Global Programme on AIDS has developed a plan focusing on education as the crucial element in AIDS prevention and control and recognizing the need for AIDS prevention and control to be integrated into national health systems, with strong international leadership, coordination, and cooperation. Many international agencies are contributing their energies to the global AIDS plan. The world would have been defenseless if the epidemic had appeared 50 years ago. However, it now has established the concept and infrastructure of primary health care, is applying social and behavioral sciences to public health information and education strategies, and has an emerging global capacity for action. Photographs.