The human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) is one of the world's most pressing global health challenges. Since the beginning of the epidemic, more than 60 million people have been infected with HIV, approximately 30 million of whom have died of HIV-related causes. As of 2009, there were 33.3 million people living with the virus, the vast majority of whom live in sub-Saharan Africa. Expanded access to antiretroviral therapy over the past decade, due in large part to U.S. support, has contributed to declines in deaths among people living with HIV. Nonetheless, new infections continue to outpace access to treatment. This book provides information on key components of the HIV/AIDS epidemic and an examination of determining how, and to what extent, the United States should respond to the continued challenge of global HIV/AIDS.