Biofortification refers to the process of enhancing the micronutrient density of crops. It emerged as a response to the public health problem of micronutrient malnutrition, referred to as hidden hunger, which seriously affects millions of people worldwide. The premise of biofortification is that nutrition of poor people can be improved if they consumed staple crops rich in micronutrients since their diets are dependent primarily on few staples they grow and eat. Since maize is an important crop for millions of people, this chapter looks at biofortification of maize with provitamin A carotenoids, purpose, methods and results, using the Zambia maize biofortification program as a case study.