Adolescence is a time of dramatic change leading to physical and sexual maturity. Although early theories emphasized storm and stress, recent research shows that serious psychological disturbance is not common during the teenage years. On the average, girls experience puberty 2 years earlier than do boys. In addition to heredity, nutrition and health-related factors affect maturational timing, influencing a secular trend toward earlier maturation in industrialized nations. Timing of puberty affects the psychosocial adjustment of girls and boys in opposite ways. The experience of puberty is also affected by school and cultural factors.

Puberty is related to increased moodiness and a mild rise in parent–child conflict, and is accompanied by new health concerns. Eating disorders, adolescent parenthood, sexually transmitted disease, and alcohol and drug abuse are some of the most serious health concerns of the teenage years. During adolescence, both sexes improve in motor performance, with boys showing much larger gains than girls. Girls continue to receive less encouragement and recognition for athletic skills.

During Piaget’s formal operational stage, adolescents become capable of abstract reasoning. Information-processing theorists agree with the broad outlines of Piaget’s description of adolescent cognition. However, they refer to a variety of specific mechanisms for cognitive change and identify one, metacognition, as central to the development of abstract thought. Dramatic cognitive changes are reflected in many aspects of daily behavior, including the ability to use scientific reasoning and typical reactions such as argumentativeness, self-concern, insensitive remarks, and indecisiveness. By adolescence, boys are ahead of girls in mathematical performance. This gender gap results from both heredity and social pressures.

School transitions create new adjustment problems for adolescents. Parents, peers, and characteristics of classroom environments affect school achievement. Family background and school experience combine to influence dropping out of school, a serious problem in the United States.