In much of the world, tuberculosis (TB) remains the leading killer of young adults, in spite of the fact that effective chemotherapy has existed for 50 years. The epidemiology of TB, with its persistence in poor countries and resurgence among the poor of many industrialized nations, causes consternation among those charged with protecting the public's health. Two factors, ostensibly biological in nature, are commonly cited to explain this setback: the advent of HIV and the emergence of TB strains resistant to multiple drugs (MDR TB). But the strikingly patterned occurrence of MDR TB-in the United States afflicting those in homeless shelters and in the inner city, for example-speaks to some of the large-scale social forces at work in the new epidemic, which began before the advent of HIV. These forces (which include poverty, economic inequality, political violence, and racism) are examined through the experience of a young Haitian man with MDR TB, a disease never before described in Haiti. Insights from this case, and from other research on TB and HIV disease, are considered in the light of past anthropological writings on TB. It is argued that, often, social scientists mar contributions to an understanding of TB by making "immodest claims of causality" regarding its distribution and course. Alternative strategies for future sociomedical research on MDR TB are proposed.