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Milestones for Ages 15 to 18

Topic Overview

Ages 15 to 18 are an exciting time of life. But these years can be challenging for teens and their parents. Emotions can change quickly as teens learn to deal with school, their friends, and adult expectations. Teen self-esteem is affected by success in school, sports, and friendships.

Teens tend to compare themselves with others, and they might form false ideas about their body image. The influence of TV, magazines, and the Internet can add to a teen's poor body image.

Physical development

Teens in this age group:

  • Usually enter puberty by age 15.
    • Most girls have had their first menstrual period by age 15.
    • By age 15, girls are near their adult height.
    • Boys usually continue to grow taller and gain weight through their teen years.

Thinking and reasoning (cognitive development)

Teens in this age group:

  • Begin to see issues in shades of gray instead of black and white.
  • May understand that people can see the same issue in different ways, but often feel that their personal views are the ones that are most correct.
  • May think they "know everything."

Emotional and social development

Teens in this age group:

  • Try to find their place in the world. They are figuring out "Who am I?" and "How do I fit in?"
  • May have emotional swings from day to day.
  • Seem mature at times, but still have periods of childish behavior.
  • May rebel and have difficult behavior.
  • Begin to seek intimate relationships, which become an important part of their identity.

Sensory and motor development

In this age group:

  • Boys continue to get stronger and more agile even after puberty.
  • Girls tend not to gain any more strength or agility after puberty.


Current as of: September 20, 2021

Author: Healthwise Staff
Medical Review: John Pope MD - Pediatrics
Kathleen Romito MD - Family Medicine


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