The biological importance of selenium has been firmly established by scientists for its intricate roles in various biochemical and physiological mechanisms related to animal and human health. To evaluate different facets of selenium in today's complex environment and to provide a worldwide platform for multi-disciplinary selenium researchers, the 6th International Conference on Selenium in the Environment and Human Health was held from 27 to 30 October 2019 in Yangling/Xi'an, China. This proceedings volume brings together 103 extended abstracts prepared by contributors from academia, industry, and governmental agencies in 18 countries, including some most recent research findings among different selenium research disciplines from cell molecular and plant biology, geochemistry, biofortification, to environmental and health management. Selenium researchers worldwide provide extraordinary new knowledge on selenium in the peer-reviewed texts contained within this book.