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, infancy, 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 upbringing and guidance of children (parents, educators, social workers) and to the young people themselves who are interested in knowing the developmental changes that have occurred and are occurring in their physical and mental selves and to acquire 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.