The Human Genome Project (HGP) is one of the largest scientific endeavors in history, and researchers hope that it will lead to breakthroughs in all areas of biology, from basic science to clinical medicine. The HGP is relevant to epidemiologists because it provides data that can be used to identify genes that are associated with predisposition to disease. In addition, the HGP provides insight into the ancestral origin of modern human populations, which may provide clues about the geographic distribution of diseases. This entry reviews the history of the HGP, as well as the goals and outcome of the project.