The application of modern molecular genetic and biologic techniques to infectious disease epidemiology dramatically improves measurement of disease and putative risk factors, increasing our ability to detect and track outbreaks, identify risk factors and detect new infectious agents. However, integration of these techniques into epidemiologic studies also poses new challenges in the design, conduct, and analysis. We examine these opportunities and methodologic challenges giving specific examples. The book will be written for the reader with limited understanding of genetics, biology and epidemiology.