The Handbook of Epidemiology provides a comprehensive overview of the field and thus bridges the gap between standard textbooks of epidemiology and dispersed publications for specialists. It reviews the key issues and methodological approaches pertinent to the field, and includes coverage of topics that are usually missing in standard textbooks and that are only marginally represented in the specific literature. It also covers innovative areas such as molecular epidemiology, ethical aspects, practical field work, health systems research, quality control, and good epidemiological practice. Each chapter is written by one or more leading scientists.