Since the epidemic first started in 1981, the human immunodeficiency virus (HIV) and the end-stage condition associated with infection with HIV, acquired immunodeficiency syndrome (AIDS), have claimed the lives of 25 million people worldwide (Fernandez & Ruiz, 2006). It is important to note that throughout this chapter we use the term “HIV/AIDS” to refer to individuals infected with HIV as well as those individuals diagnosed with AIDS. However, we will use the term “HIV” when referring only to individuals diagnosed as being infected with HIV and “AIDS” when referring specifically to individuals whose HIV disease has progressed to AIDS. We first address the progression of HIV disease, followed by a review of prevalence of HIV and AIDS both within the United States and globally. ...