The Adolescent Stage of Human Development

Around the age of 11 or 12, your loving, carefree child may become a stranger, but the changes you see in mood and behavior are likely normal and indicate your child is the adolescent stage of development. Every teen goes through a series of developmental milestones in order to enter adulthood, but it is important to keep in mind that social, physical and emotional changes can vary slightly from one teen to another.

While physical and emotional growth varies, the feelings and behaviors of each stage are generally similar. (Image: Digital Vision./Digital Vision/Getty Images)

The Adolescent Stage of Development

Adolescent development typically begins around 11 years of age and continues until 19 to 21 years. The developmental stages of adolescence, which include physical, cognitive and social emotional development, are divided into early, middle and late adolescence. The goal of adolescent development is to move toward a more mature sense of self and purpose. Teens learn how to establish and maintain healthy relationships, share intimacy comfortably and to understand abstract ideas and develop their own moral viewpoints.

Physical Development

Between 11 and 13 years, many physical changes occur as teens enter early adolescence. Teens at this age start to grow body hair and gain height and weight rapidly. Breast and hip development and menstruation begin in girls, and boys experience a deepening of voice. Between the ages of 14 and 18, middle adolescence begins and physical growth slows for girls. In boys, growth continues to late adolescence, which occurs between 19 and 21 years of age. While girls are fully physically developed by the beginning of late adolescence, young men will continue to gain weight, muscle mass, body hair and height. According to the University of Maryland Medical Center, it is not uncommon for teens in early adolescence to compare themselves with peers and become sensitive and self-conscious about their bodies.

Cognitive Development

In early adolescence, teens show a growing capacity for abstract thought. Their intellect expands and knowledge becomes more important. Teens between 11 and 13 will also show the ability for deeper moral thinking. As teens move into middle adolescence, their capacity for abstract thought continues to increase. They are interested in setting goals and in moral reasoning. By late adolescence, teens are able to think ideas through, delay gratification and examine their inner emotions and experiences. They show an increased concern for the future and continue to be interested in moral reasoning.

Social Emotional Development

Teens struggle with their sense of identity during early adolescence and tend to feel awkward about their bodies and worry about being normal. Teens at this stage of development begin to see that Mom and Dad aren't perfect, and conflicts may arise as their desire for independence and the influence of their peer group increase. Moodiness, testing boundaries and a greater interest in privacy are concerning but indicate normal social emotional development. Peer groups in early adolescence usually consist of platonic friendships, and members typically share interests and behave and dress in a similar fashion. As teens approach middle adolescence around the age of 14, they become intensely self-involved and have high expectations of themselves that can lead to poor self-image as they continue to adjust to their changing bodies and worry about normalcy. According to Head Start, during middle adolescence teens are increasingly reliant on friends as they distance themselves from parents. Feelings of love and passion also develop at this stage, and peer groups expand to include romantic friendships. After the age of 18, when late adolescence begins, teens show a stronger sense of identity and emotional stability and are more independent and self-reliant.