『Adult and Gerontological Psychology』 is composed of five parts.
Part 1 covers the historical background and prospects of adult development, theories of adult development, and research methods for adult development as the foundation of adult development. Parts 2, 3, and 4 cover the major developmental characteristics of adulthood, middle age, and old age, including physical development, cognitive development, vocational development, personality and social development, and family life, respectively.
And in Part 5, we organized the topics of death and dying, bereavement and grief, and reflection on life, in the sense that it is the final stage of human development.

This fourth edition has particularly focused on integrating new domestic and international research conducted over the past five years since the publication of the third edition in 2019.
We have tried to introduce as many recently published studies as possible, and have also replaced statistical data with more recent data.
In particular, in the section on 'cognitive development' in adulthood, Schaie's more detailed summary of the stages of cognitive development in adulthood was introduced.

In the 'Health and Disease' section of midlife, the American Heart Association (AHA) introduced guidelines for preventing cardiovascular disease.
And in the 'Elder Abuse' section, the types of elder abuse are described in more detail, dividing them into physical abuse, emotional abuse, sexual abuse, economic abuse, and neglect.

Among the 'physical changes' in old age, we have summarized chronic obstructive pulmonary disease (COPD) and emphysema in the respiratory system.
Diabetic retinopathy was added to the visual section of ‘Changes in sensory function’ in old age.
In the section on 'aging theory' in old age, information on telomeres was added.
And in the ‘cognitive change’ section, ‘future memory’ was added in addition to ‘past memory’.