The spread of human immunodeficiency virus (HIV) is believed to result from HIV-infected individuals who are unaware of their infection and, thus, the possible consequences of their sexual behavior for others. However, differential rates of HIV infection between countries may reflect a different set of circumstances. We obtained data from the World Bank and several other sources to test eight alternative explanations for the global differences in prevalence of HIV infection: (1) economic underdevelopment, (2) inadequate public health care, (3) insufficient media, (4) political instability, (5) overurbanization, (6) social inequity, (7) religion, and (8) region. Our regression findings showed that income inequality and political instability had statistically significant positive effects on HIV/AIDS prevalence and that gender equality had a negative effect on HIV/AIDS prevalence. Religion and region were also important predictors, as countries that were predominately Muslim and Christian Orthodox generally had lower prevalence of HIV/AIDS, whereas West Africa, Central Africa, and Southern Africa had a higher prevalence of HIV/AIDS. None of the public health and media indicators were statistically relevant.