HomeHealth & BehaviorHealth & Nutrition

Child Development: 13- to 16-Year-Olds

Read about typical physical, intellectual, and social growth that kids experience during middle adolescence.

By Nancy Firchow, M.L.S.

Middle adolescence is a time of blossoming development - the insecure, inwardly focused 13-year-old becomes a cheerful, charming 16-year-old looking toward the future. During this time your child's thinking skills take a decidedly adult turn, his body matures, and friends and social networks outside the family become increasingly important. Now is when you will really begin to get a glimpse of the adult your child will become.

Physical Development

Boys and girls still exhibit markedly different levels of physical maturity as they enter middle adolescence. Girls' rapid growth is generally tapering off, while many boys have yet to see the beginning of their much anticipated growth spurt. By the end of this period most girls will be near their adult height; boys may continue to grow until age 18 or 19.


  • growth in height continues, but at a slower pace than earlier; adult height is reached by age 16 or 17
  • breast development continues
  • pubic hair thickens, darkens, and takes on adult triangular pattern
  • underarm hair thickens
  • hips widen; fat deposits in buttocks, legs, and stomach increase
  • menstrual periods become regular; ovulation is established; pregnancy becomes possible


  • rapid growth in height and weight
  • muscles fill out and strength increases dramatically
  • voice deepens
  • pubic and underarm hair appears and thickens
  • body hair increases
  • penis, scrotum, and testes enlarge
  • ejaculation and nocturnal emissions occur

Both Girls and Boys:

  • always hungry; appetite is great
  • need for sleep increases; may sleep quite late on weekends
  • oily skin and acne may be problematic
  • sweating increases
  • rapid growth may cause clumsiness and lack of coordination
  • sexual desires and fantasies increase

Intellectual Development

Between 13 and 16 your child's ways of thinking about himself, others, and the world shift to a much more adult level. He enters middle adolescence with a focus on things he can experience here and now, and moves to being able to imagine the range of possibilities life holds. Expect the following changes as a progression of development rather than as age-based milestones:

  • arguing skills improve (and are demonstrated often and with great passion)
  • reasoning skills improve:
  • begins with the ability to apply concepts to specific examples
  • learns to use deductive reasoning and make educated guesses
  • learns to reason through problems even in the absence of concrete events or examples
  • becomes able to construct hypothetical solutions to a problem and evaluate which is best
  • focus on the future develops:
  • begins with a present focus, mixed with some fantasy
  • learns to recognize that current actions can have an effect on the future
  • starts to set personal goals (and may reject goals set by others)
  • decision-making skills improve:
  • begins to independently differentiate right from wrong and develops a conscience
  • learns to distinguish fact from opinion
  • learns to evaluate the credibility of various sources of information
  • becomes able to anticipate the consequences of different options
  • may challenge the assumptions and solutions presented by adults

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