During her teenage years, specifically from ages thirteen to fifteen, Frank lived in hiding with her family. Many readers find her emotions and experiences relatable, highlighting how the journey of growing up—with all its challenges, joys, and uncertainties—remains unchanged regardless of time, place, or situation. Adolescence is often a period of awkwardness and self-reflection, but Frank’s unique circumstances intensified these feelings. Like many teenagers, Frank experienced conflicts with her family, especially with her parents. Her tense relationship with her mother is a typical aspect of adolescence, as girls begin to assert their independence. Unlike most teenagers, however, Frank couldn't physically distance herself from her mother, which only widened the emotional gap between them. Frank's preference for her father became more evident due to their close living quarters, although her desire for independence eventually created some distance between them as well. Her relationship with her sister, Margot, was also typical; she felt unfairly compared to Margot, who was perceived as the ideal teenager by their parents. On July 12, 1942, she wrote, ‘‘[E]very day I feel myself drifting further away from Mother and Margot. I worked hard today and they praised me, only to start picking on me again five minutes later. You can easily see the difference between the way they deal with Margot and the way they deal with me.’’ Despite the sibling rivalry, the sisters grew closer over the years in hiding as Frank matured and they realized they had more in common than they initially thought.

Frank's teenage years were distinctive because Mr. and Mrs. Frank practiced a relatively progressive parenting style, allowing their daughters to express their individuality. The prevailing attitudes of the time were reflected by other characters, particularly Mrs. Van Daan, who was sometimes shocked by Frank’s seemingly undisciplined behavior.

At the beginning of her diary, Frank was lively, playful, and extremely curious. Her descriptions of people were typical of adolescent perceptions. For instance, on June 15, 1942, she described a classmate as ''a detestable, sneaky, stuck-up, two-faced gossip who thinks she's so grown-up.’’ Frank's self-confidence led her to believe that many boys in her class were infatuated with her. On June 20, 1942, she noted, ‘‘I have a throng of admirers who can't keep their adoring eyes off me and who sometimes have to resort to using a broken pocket mirror to try and catch a glimpse of me in the classroom.’’ Her interest in the opposite sex and her desire to appear attractive to boys were perfectly normal for a girl her age. Given the likelihood of not meeting any new boys for a long while, it’s not surprising that she reminisced about her previous admirers.

As Anne Frank's diary progresses, she increasingly uncovers her own identity, separate from that of her parents. On April 11, 1944, she writes, "I'm becoming more and more independent of my parents. ... If only I can be myself, I'll be satisfied. I know that I'm a woman, a woman with inner strength and a great deal of courage!" By her final entry, she has achieved a deeper self-awareness, recognizing that she still has much to learn about herself and the world around her. Frank begins to comprehend her complex identity, acknowledging both her strengths and weaknesses, while also forming a clearer vision of the woman she hopes to become.

Many readers find Anne Frank's romance with Peter to be predictable. They are at an age where young people become more aware of their sexuality, and Peter and Anne have only each other to explore these feelings with. Although Anne enjoys Peter's company and looks forward to their meetings, she understands they are not truly in love. On February 18, 1944, as their relationship begins to develop, she writes, "Don't think I'm in love, because I'm not, but I do have the feeling that something beautiful is going to develop between Peter and me, a kind of friendship and a feeling of trust." Amidst this budding romance, Anne experiences typical teenage emotional turmoil; on February 28, 1944, she admits, "I see him nearly every hour of the day and yet I can't be with him, I can't let the others notice, and I have to pretend to be cheerful, though my heart is aching." However, as she gets to know Peter better, she realizes she is further along in her journey of self-discovery than he is and is quickly outgrowing him.