Early childhood is a crucial period in a child’s development. This special feature focuses on the perinatal period and early childhood up to age 3. The goal is to provide professionals with insights into the knowledge and conditions necessary for a child’s development. In particular, it addresses how to address socio-environmental determinants with a focus on prevention and health promotion. About twenty experts contributed to this issue. Also in this issue: a survey on adolescents’ knowledge of nutritional guidelines, an overview of knowledge and best practices for promoting physical activity among these same adolescents, as well as a section dedicated to the prevention of lead poisoning.