There is increasing emphasis on interdisciplinary “translation” in biomedical research. A major push towards prevention of Alzheimer's Disease is spawning translational research that should span basic, clinical, and population investigations. Epidemiological studies, which address our understanding of risk and protective factors for disease at the population level, are contributing less than they could to translational research. In part, this is because the key concept of risk is being “lost in translation,” muddling interpretations and leading to interdisciplinary frustrations. Two epidemiologists offer a framework for resolving some of the confusion.