Selenium plays a significant role in preventing certain types of cancer and cardiovascular diseases. The level of Selenium in the human body depends on its concentration in food. In turn, the content in vegetable crops is a function of the soil-plant system. There are many countries in the world with low Selenium content in the soil. The average daily human intake is thus limited through food chain. Analysis of Selenium status suggests that fortification of the soil substrate with Sodium Selenate, and foliar application to agricultural crops are both effective means of Selenium enrichment. Our intention for this publication is to present the possibilities of augmenting Selenium content by biofortification of soils and plants through differentiated nutrition. In the first part of the monograph, the results of Selenium supplementation in model vegetation experiments are presented. The next part of the monograph presents the results of foliar supplementation of Selenium in field conditions. This book is an outstanding reference source for plant breeders and researchers engaged in biofortification of horticulture crops. It is also beneficial to agricultural companies and other stakeholders.