It's fiction. The Outsiders is a work of imagination, not based on real - life events in a documentary sense. It creates a fictional world with fictional characters to tell a story about youth, class differences, and friendship.
It depends on your perspective. Some consider 'The Outsiders' historical fiction because it reflects the cultural and social aspects of a particular era. However, others might argue it's more of a coming-of-age story with historical backdrop.
To some extent, it is. 'The Outsiders' takes place in a past setting and reflects the circumstances and issues of that time, which are typical characteristics of historical fiction.