Adolescence is the transition period from childhood to adulthood, extending from puberty to social independence. Boys seem to benefit (though with risks) from “early” maturation, girls from “late” maturation. The brain’s frontal lobes mature and myelin growth increases during adolescence and the early twenties, enabling improved judgment, impulse control, and long-term planning.

Piaget theorized that adolescents develop a capacity for formal operations and that this development is the foundation for moral judgment. Lawrence Kohlberg proposed a stage theory of moral reasoning, from a preconventional morality of self-interest, to a conventional morality concerned with upholding laws and social rules, to (in some people) a postconventional morality of universal ethical principles. Other researchers believe that morality lies in moral intuition and moral action as well as thinking. Some critics argue that Kohlberg’s postconventional level represents morality from the perspective of individualist, middle-class people.

Erikson theorized that each life stage has its own psychosocial task, and that a chief task of adolescence is solidifying one’s sense of self—one’s identity. This often means trying out a number of different roles. Social identity is the part of the self-concept that comes from a person’s group memberships.

During adolescence, parental influence diminishes and peer influence increases, in part because of the selection effect—the tendency to choose similar others. But adolescents also do adopt their peers’ ways of dressing, acting, and communicating. Parents have more influence in religion, politics, and college and career choices.

The transition from adolescence to adulthood is now taking longer. Emerging adulthood is the period from age 18 to the mid-twenties, when many young people are not yet fully independent. But observers note that this stage is found mostly in today’s Western cultures.