Adolescence

Adolescence, period of life between childhood and full adulthood (between 12 and 20 years of age). Its physical manifestation is puberty, the development of sex characteristics, making possible sexual union and reproduction. Physical changes include the development of breasts in girls, changes in voice in boys, and the appearance of pubic hair in both. Adolescence is of psychological interest because of the changes in attitudes, emotional responsiveness, and social behavior that accompany this sexual maturation.

See also: Developmental psychology; Growth.