Her most famous works, like *The Outsiders* and *That Was Then, This Is Now*, deal with themes of youth, adolescence, social issues, and the struggle for identity. These themes resonated strongly with young readers, earning her a dedicated following and solidifying her place in the history of YA literature.
While primarily known for YA fiction, her later works like *Rumble Fish* and *Tex* also included elements of crime fiction and western fiction. However, even in these novels, the core themes of youth and growing up remained prominent.