This course aims to present the manifestations of growth since the moment of fertilization, covering in explanation and detail the developmental manifestations in all their physical, motor, mental, cognitive, linguistic, emotional, and social aspects, as well as a presentation of the concepts, principles, and theories concerned with the psychology of development and research methods in them. Then we conclude the book with the most prominent problems. Developmental and behavioral issues in the lives of children and adolescents, trying to find practical solutions to them