Both on national and international levels, the acquired immunodeficiency syndrome (AIDS) represents a formidable challenge to social institutions and to cultural assumptions. Its effect thus far, in what must be considered the very early stages of a protracted and unprecedented epidemic, has been to exacerbate existing social tensions and divisions over a surprisingly wide field. Though international leadership by the World Health Organization has been met with an unusually high degree of multinational cooperation, AIDS has also stimulated a degree of xenophobia and racial friction that, if allowed to grow, could handicap global AIDS control and prevention efforts.