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. *Presents the key points of consideration when integrating molecular biology and epidemiology *Discusses how using molecular tools in epidemiologic research affects program design and conduct *Considers the ethical concerns that arise in molecular epidemiologic studies *Provides a context for understanding and interpreting scientific literature as a foundation for subsequent practical experience in the laboratory and in the field.