Selenium is arguably the naturally occurring trace element of greatest concern worldwide. In excessive amounts it can lead to toxicosis and teratogenesis in animals, while the impact of selenium deficiency can be even more significant. Contributors from 22 countries explored the connections and inter-relationships between selenium in the environment, agriculture, human and animal health, and molecular and biochemistry processes to complete this book containing 90 peer-reviewed extended abstracts. The text represents glimpses of the presentations that were delivered at the 3^rd International Conference on Selenium in the Environment and Human Health in 2013 in Hefei, China. We are indebted to the international authors representing a multitude of disciplines from academic, industry, and governments for sharing their extraordinary new knowledge on selenium research.