The work describes and interprets the changes that occur in the mental life of the young individual, from conception to the 20th year.

It covers all periods of human development (intrauterine, infant, childhood, adolescence) and all areas of human personality (physical, motor, sensory, cognitive, linguistic, emotional, social).

It is addressed to both students attending applied psychology courses and the general public, and especially to adults who are responsible for the education and guidance of children (parents, educators, social workers) and to the young and post-adolescents themselves who are interested in understanding the developmental changes that have occurred and are occurring in their physical and psychological selves and acquiring a deeper self-awareness.

It consists of four (4) volumes.
Volume 1 examines the intrauterine period and infancy,
Volume 2 the preschool age,
Volume 3 the school age, and
Volume 4 the adolescent age.