This Topic Guide has been compiled to provide an overview of undernutrition in the context of development. The focus of the Guide is on undernutrition, defined as the outcome of insufficient (quantity and quality) of food intake (hunger) and repeated infectious diseases. Undernutrition includes being underweight for one’s age, too short for one’s age (stunted), underweight for one’s height (wasted), and deficient in vitamins and minerals (micronutrient malnutrition). This review does not focus on the other component of malnutrition, which is overnutrition