The most popular of Cormier's novels for young adults, and the one with which he is most identified, The Chocolate War is a book that incites extreme opinions in most of its readers. The majority of critics either find the book offensive or excellent - very few are lukewarm about its value. It is a book of beguiling simplicity that nevertheless explores universal human themes about the struggle against oppression and a pack mentality, and the assertion of character during the formative years of young adulthood.
The book has been banned more often than any of Cormier's other novels, and is considered by many to be an offensive work that presents a skewed version of reality. It has also been lauded as a strikingly realistic story of the struggles of young people, both against authority and within themselves.
The Chocolate War is set in a middle-class private high school run by Catholic brothers, in the fictional town of Monument, Massachusetts (a town much like Robert Cormier's hometown of Leominster). There is a conflict between the student body and the temporary headmaster over the annual sale of chocolates for the benefit of the school. A secret group of boys called "The Vigils", which effectively controls the school, becomes involved with the battle over whether or not to sell chocolate, and encourages certain boys to take sides. One boy, Jerry Renault, finds that he cannot abide the hypocrisy of either the school or The Vigils, and strikes out on his own road. When the conflict comes to a head the boys are left to fend for themselves, bereft of parents or other caring adults to show them what to do.
The novel was made into a film in 1988, and Cormier later wrote a sequel involving the same characters, Beyond The Chocolate War. The book has consistently been popular with young readers, and has been assigned in many high school classrooms since its publication in 1974. During his lifetime, Cormier received many calls and letters from young readers with questions about the book and the characters, which he always personally answered. The book has never been out of print, and has been converted into a two-act play sometimes produced in high schools and theatre clubs. It won the New York Times' Outstanding Book of the Year, the ALA Best Book for Young Adults, the School Library Journal Best Book of the Year, and the Lewis Carroll Shelf awards, among other awards.