This chapter begins by identifying concerns of two fields with applied ethnographic research on health programs. It outlines some of the limitations of research to date and focuses on a variety of anthropologically-based studies on diarrhea. The chapter demonstrates that the puzzles presented to health professionals in using ethnographic data are better resolved through further ethnographic research, not by rejecting this research. Public health studies of diarrheal disease often note the social preconditions of ill health-poor water storage or availability, dirt floors, lack of separate utensils and cooking vessels, shortage of firewood-as confounders of major hypothesized biological relationships. The domestic environment in a fuller sense is a field or locale where biological, social, cultural, economic, and political institutions play out their impact on the child. Efforts to describe local responses to one of the world’s most common diseases offer a challenge to anthropological and other social science theory.