This document discusses psychological adaptation in adulthood. It defines adulthood as the stage when an individual has completed growth and is ready to take on a role in society alongside other adults. It divides adulthood into early adulthood (ages 18-40), middle adulthood (ages 41-60), and late adulthood (ages 60+). It outlines the biological, legal, educational, and psychological criteria for entering adulthood. It describes the typical characteristics, tasks, needs, and physical and psychological development of each phase of adulthood.