The time during your teens when you become sexually mature is called puberty. It is a physical change that usually happens between ages 10 and 14 for girls and ages 12 and 16 for boys. 

Some changes occur in both boys and girls, including 

• Growing taller 
• Weighing more 
• Acne  
• Growing underarm and pubic hair 

In addition, girls develop breasts and begin their periods. Boys become more muscular, their voices deepen, and their penises and testicles become larger. You might also notice changes in the way you think and feel.  

Normal Adolescent Development Part II 

Late High School Years and Beyond 

Parents are often worried or confused by changes in their teenagers. The following information should help parents understand this phase of development. Each teenager is an individual with a unique personality and special interests, likes and dislikes. However, there are also numerous developmental issues that everyone faces during the adolescent years. The normal feelings and behaviors of the late high school adolescent are described below. 

Movement towards Independence 

• Increased independent functioning 
• Firmer and more cohesive sense of identity 
• Examination of inner experiences 
• Ability to think ideas through 
• Conflict with parents begins to decrease 
• Increased ability for delayed gratification and compromise 
• Increased emotional stability 
• Increased concern for others 
• Increased self-reliance 
• Peer relationships remain important and take an appropriate place among other interests 

Future Interests and Cognitive Changes 

• Work habits become more defined 
• Increased concern for the future 
• More importance is placed on one's role in life 

Sexuality 

• Feelings of love and passion 
• Development of more serious relationships 
• Firmer sense of sexual identity 
• Increased capacity for tender and sensual love 

Morals, Values, and Self-Direction 

• Greater capacity for setting goals 
• Interest in moral reasoning 
• Capacity to use insight 
• Increased emphasis on personal dignity and self-esteem 
• Social and cultural traditions regain some of their previous importance 

Older teenagers do vary slightly from the above descriptions, but the feelings and behaviors are, in general, considered normal for each stage of adolescence.