Melinda is miserable at the beginning of the novel but unable to say why. She knows why, but she can't put it into words, not even in the privacy of her sharp inner monologue. She is talented at pointing out the absurdities of high school bureaucracy, such as when the principal and administrators prioritize everything but students' interests, but while quick-witted internally, Melinda cannot bring herself to speak aloud. She also can't find the words to define what happened to her, and thus cannot defend herself against unfair accusations from students and teachers.

Although she cannot put it into words, Melinda is experiencing post-traumatic stress disorder, or PTSD, for most of the book. Her initial response to the trauma is to pretend it didn't happen. Rather than admit the truth and do the work it takes to heal, Melinda thinks she can  skip the pain and just move on. But her trauma doesn't go away. Random details trigger memories of the trauma and take her back to the attack. Melinda freezes and vomits when Andy comes close enough to her that she can smell him because his scent fills her with the same fear she felt during the attack. In many scenes, Melinda describes being sucked away from reality, such as when David holds down the frog in science class. Suddenly, the teacher's voice seems far away as Melinda is pulled back into her bad memories. Through much of Speak, Melinda exists in a state of denial, opting to proceed like nothing happened to her. She befriends Heather because she is supposed to have a friend, not because she likes her. She goes to class, but her mind is on everything but what is being taught. She goes through the motions of life in an effort to look as if she is not suffering on the inside and often refers to everyday parts of life as playacting because she feels so removed from them. However, when she encounters something that forces her mind back to the night of the party, the reaction is physical as well as mental. When David holds down the frog, Melinda freezes and finds herself replaying the assault in her mind. For all her efforts to forget what happened, she is often overcome by reminders in her daily life.

Although Melinda is determined to get better, she doesn't know what will help. Unlike physical injuries, emotional trauma has no clear path of recovery. She hates herself for not being able to forget the attack and move on. Until she reaches out for support, Melinda has no way of knowing that she is suffering from common after-effects of assault. Through Mr. Freeman’s art project, Melinda relearns how to express herself and is able to begin verbalizing her emotions, and thereby begin processing the attack.