The importance of reputation is the first of two central themes in Thirteen Reasons Why. Hannah traces the beginning of the end for her to Justin, the boy with whom she shared her first kiss. Their kiss was chaste and innocent, but in Justin's mind, it became something more, and he began to brag. As Hannah accurately puts it:

a rumor based on a kiss started a reputation that other people believed in and reacted to...(creating) a snowball effect.

As Clay realizes when he listens to the tapes, "(Hannah's) reputation started in Justin Foley's imagination," and because Justin sets the precedent with his gossip, a second incident occurs that is even more damaging than the first. His attention having been drawn to Hannah as a sex object, Alex, who had been her friend, lists Hannah as "Best Ass in the Freshman Class," unintentionally but irrevocably changing the way people perceive her, and making her life a living hell. Hannah above all yearns to establish meaningful relationships with others, but individuals like Clay who might have made a difference in her life stay away because they are afraid of her reputation. Instead, Hannah is continually approached by boys who have only one thing on their minds, and the constant harassment soon renders Hannah unable to trust anyone, further increasing her isolation. After being objectified and betrayed time after time, Hannah, completely beaten, finally allows herself to succumb to the reputation set for her, and follows this capitulation by taking her own life.

A second theme examined in the book, a theme which is closely related to the first, is the issue of responsibility. Very few of the characters actually set out to hurt Hannah, but because they give little thought to the significance of their actions, they end up playing a part in the total destruction of her life. Hannah addresses this fact up front, telling her listeners:

I know you didn't mean to...

(The entire section is 815 words.)