Medical anthropology is a dynamic subdiscipline that focuses on the complex and often conflicted borderlands between health, biology, the environment, culture, and human social relationships and actions. In HIV/AIDS research, for example, medical anthropology asks questions like these: Can we really understand the AIDS epidemic and respond to it effectively by only studying the biology and pathology of the human immunodeficiency virus? What aspects of peoples lives do we need to understand to find, reach, and productively engage those who are at greatest risk for HIV infection? What social structural and local situational factors contribute to people’s involvement in risky behaviors? What do people know, believe, and feel about AIDS? How do these social, cultural, and biological factors influence behavior of at-risk individuals, patients, health care providers, and society? How should we interact with patients in clinical and testing centers? How does the stigma associated with HIV/AIDS impact those living with it? Further, if we think about the AIDS epidemic as a global problem, with different routes of infection, different populations, different beliefs and behaviors, different health care systems in different parts of the world or even different parts of a single country, we begin to gain a sense of why a social science like anthropology and its hallmark qualitative research methods have had such a significant role in addressing the AIDS epidemic since the 1980s. In other words, while biomedical understandings of AIDS are central to prevention and treatment, social science provides equally important information crucial to the fight against the AIDS epidemic. Many of these same factors apply in the study of other diseases and health conditions domestically and internationally.