There is ample evidence that early-life nutrition plays a powerful role in programming a person’s development, metabolism and health for the future. Optimizing early nutrition may reduce the risk of cardiovascular diseases, allergies, diabetes and obesity, and positively influence immune function as well as cognitive and behavioral outcomes later in life. The first part of this book covers the impact of nutrition on the immune system, the role of gut microbiota in the immune status, as well as the prevention and management of food allergies in children. The second part is dedicated to obesity prevention: experts in epigenetics and metabolic programming share scientific evidence on the use of biomarkers for predicting the risk of early obesity. They also discuss potential strategies for interrupting intergenerational cycles of obesity during pregnancy, early infancy and childhood. The last part covers complementary feeding and its importance in short- and long-term health, and how it can affect behavioral and psychological aspects, as well as food preferences in later life.