Why is The Outsiders banned?

S.E. Hinton's The Outsiders is considered dangerous by some people because it depicts violence as well as behaviors that are not deemed acceptable in minors, like drinking and smoking. Additionally, the portrayal of the Curtis brothers and the lives of their friends, like Johnny Cade, reveal uncomfortable realities of familial instability and the damaging effect it can have on adolescents. Some groups who have banned the book felt that the book's descriptions of the conflicts between the Greasers and the Socs idealized and glamorized gangs and gang warfare. Some families have protested the book because they felt that the bad language, the deaths, and the violence were all too harsh for their children, who were not ready to read about such events in a novel. The focus on troubled young people and the absence of positive adult role models in The Outsiders is also problematic to some people.

The Outsiders by S.E. Hinton may be banned in areas where parents and guardians believe it contains too much "mature" content and would negatively impact their children. For instance, multiple scenes center around gang violence, a result of the mounting tension between the Greasers and the Socs. Ponyboy's group of friends also swear, curse, smoke, drink, and pursue girls with patently sexual intentions. 
The predominant reason why schools remove this book from the curriculum, however, is the depiction of gang violence. However, religion played a rather large role in promoting the idea that this was a "bad" book and exposed children to unseemly content. In the late 1960s and early 1970s, following the 1967 publication of the book, Christian groups mobilized around banning the book in American schools, saying it contained and encouraged "ungodly" themes and behavior not suitable for teenagers.