Adolescent Children

Adolescence is a developmental period within the human life span that separates childhood from adulthood. It is marked by multiple transitions such as the onset of puberty and its corresponding rapid developmental growth, cognitive gains, transitions in schooling, shifts in familial and social relationships, and increasing autonomy and choice. Adolescence is typically considered to begin when a child reaches age 13; however, many biological, social, and psychological changes have already begun in the preadolescent years.

Puberty refers to the physical changes that occur as a child's body becomes capable of reproduction. Pubertal changes include rapid physical growth; redistribution and/or increases in body fat and muscle tissues; acquiring secondary sexual characteristics, such as breasts and pubic hair; menarche (for girls); and spermarche (for boys). Other changes that occur with puberty include acne and increases in body odor, strength, and endurance. Overall puberty takes five to six years to complete for most individuals. While often thought of as a marker for entry into adolescence, hormonal changes begin in middle childhood (approximately 8 years old for girls and 10 years old for boys). However, the onset of puberty can vary greatly by individual.

The adolescent period is often divided into three stages: early adolescence, middle adolescence, and late adolescence/young adulthood. Early adolescence refers to children aged 11 to 14 who are still undergoing many of the physical changes of puberty.

Other transitions that can occur at this period include multiple school transitions, increased responsibilities in the home, and an increasing desire to conform to peer influences. The middle adolescent stage includes children aged 15 to 17 years old, while late adolescence/young adulthood is typically applied to individuals between the ages of 18 and 21. While these later stages involve multiple transitions as well—including school changes, initiation of intimate relationships, and paid employment—most adolescents have achieved their adult height and full reproductive capacity by this time.

The end point of adolescence is not well defined, and often differs by culture as markers for reaching adulthood status are culturally determined. Entry to adulthood can include independent living; the ability to perform certain functions within the society, such as voting or serving in the armed forces; parenthood; and/or full-time employment. In many Western societies, adolescence has been extended into the early 20s due to increased expectations of postsecondary education and monetary dependence upon parents.