Your Daughter at 15: Milestones

Reviewed by Renee A. Alli, MD on May 04, 2021

They can be super; sweet and super moody, all in the same half-hour. And they're on their phone 24/7. Sound like your 15-year-old daughter? Even though they may think they’re all grown up, girls this age still need plenty of guidance. The more you know about what to expect, the more you can help.

A 15-year-old is an adolescent -- no longer a child, but not yet an adult either. There are lots of physical changes, but it’s also a time of big intellectual, social, and emotional development. While it can vary from girl to girl, there are common milestones to look for.


By 15, most girls have developed breasts and have pubic hair, have reached their adult height, and had their first menstrual period.

Your daughter may be concerned about the size and shape of their body and weight. Nearly half of all high school girls diet. Sometimes this concern can lead to eating disorders. If you think this may be a problem for your daughter, talk to their doctor.


When children are young, they only think about what’s going on at the moment. But by age 15, a girl can think in more complex ways about what’s possible and how the world works. Expect your 15-year-old to:

  • Start to set goals for the future
  • Plan for “what if” situations
  • Make more of their own decisions
  • Understand the effects of their behavior

They will start to develop a sense of right and wrong and use it to make decisions. But sometimes they will act without a lot of thought. Your daughter will get better at organizing themselves. Many girls this age do a good job as they juggle school, activities, and work.

Emotional and Social

15 year olds search for identity. As they figure out who they are, they will want to be more in control and more independent. At 15, girls:

  • Consider friends as important as family
  • Spend less time with parents, and more time with friends or alone
  • Start to date
  • Tend to argue
  • May become sexually active
  • May be more aware of sexual orientation
  • Feel things deeply
  • Try to understand their own feelings
  • Feel sad or depressed. If a period of sadness lasts more than a couple of weeks, get some help.
  • Experiment with alcohol, tobacco, and other drugs

Help Them Stay Safe

Teens ages 15-19 have higher rates of death than younger children. Top causes are vehicle crashes, murder, and suicide. As your daughter becomes responsible for their own safety, these rules can help keep them safe:

  • Always wear a seatbelt and never use a cell phone while driving.
  • Wear safety gear when on a bike, rollerblades, or skateboard.
  • Be careful online and using social media.
  • Follow family rules, and the law, around alcohol and drug use.
  • Understand what can happen if you are sexually active (talk to your daughter about pregnancy, diseases, and changes in how they might feel about themselves).

How You Can Help

Even though they may not always want or ask for it, your daughter is going to need your support. They may pull away from you from time to time. Don’t worry. It’s normal. Be there when they want to talk. Put down the phone, stop what you’re doing, and listen quietly. Try to understand their point of view. Then tell them what you think. Don’t laugh at or make fun of what they say. Offer words of support or encouragement. Do it as often as you can.

Here are a few more ways you can support your daughter:

  • Help your daughter start to plan for the future.
  • Encourage them to be part of family decision-making.
  • Show interest in their friends, school, and activities.
  • Set limits on the use of phones, devices, and social media. Talk about what happens if the rules are broken.
  • Teach your daughter how to say no. Make sure they know what to do if they are offered drugs or pressured to have sex. Let them know you are a phone call or text away if they want to leave a party or other gathering; if they feel uncomfortable, they are not obligated to stay.
  • Encourage them to volunteer and care about others.
  • Respect their privacy.

Help Your Girl Stay Healthy

The 5, 4, 3, 2, 1 rule is a good one to follow. Every day they should get: five servings of fruits/vegetables, four glasses of water, three servings of dairy, 2 hours of screen time, and 1 hour of physical activity.

Pay attention to warning signs of suicide. Take action if your daughter:

  • Talks about suicide or death
  • Talks about not being around in the future
  • Gives away things they love
  • Has tried suicide before

If you think they may try suicide, don’t leave your daughter alone. Get help right away.

Your 15-year-old is a blessing and a challenge. Stay close to them and help them through this important time in their life, and yours.

Show Sources


KidsHealth from Nemours: “Growth and Your 13-18-Year-Old.”

Cleveland Clinic: “Adolescent Development.”

NorthShore University HealthSystem: “Pediatrics, Teenager, (13-18 Years).”

Sutter Health Palo Alto Medical Foundation: “Partners & Teachers: Teen

Growth & Development, Years 15 to 17.”

Centers for Disease Control and Prevention: “Child Development, Teenagers

(15-17 years of age).”

Understood: “Developmental Milestones for Typical High-Schoolers.”

Cleveland Clinic: “Social Development During the Teen Years.”

Youth Suicide Prevention Program: “Know the Warning Signs.”

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