Physical changes. The growth spurt of puberty can cause a girl considerable anxiety, especially if she is behind​—or ahead of—​her peers. “I was one of the first girls to have to wear a bra, and I felt so uncomfortable with myself,” says Anna, now 20. “Compared with my peers, I felt that I was weird, as if I were a mutant!”

Emotional changes. Karen, now 17, recalls: “It was so frustrating not knowing why I would be so happy during the day and later, during the night, I would be crying my eyes out. I didn’t know what was wrong with me. It was as if my emotions were out of control.”

Onset of the menstrual cycle. “Even though my mom prepared me, my first period totally caught me off guard,” says a young woman named Kathleen. “I took several showers a day because I felt dirty all the time. Plus, my three older brothers would tease me mercilessly. They somehow thought that my whole ordeal of getting periods was funny.”

Social pressure. Marie, now 18, recalls: “When I was between 12 and 14, peer pressure was really strong. Kids in my school were mean to anyone who stood out as different.” Anita, 14 years old, says: “At my age, feeling that you are accepted by a group of friends is crucial and being left out is devastating.”