Matt Dillon didn't actually want or expect to be cast in the movie. He went to the audition just so he could skip school.
Vincent Spano, who plays Mark, was the runner-up to Matt Dillon for the larger role of Richie. Despite this, Spano volunteered to help first-time actor Dillon with the intricacies of acting, such as hitting his marks and memorizing his lines.
Originally completed in 1979, the movie was first shown in late 1979, but was not released wide in the USA until two years later. At the time, the studio thought the movie was too controversial and feared that it would spark attacks after several violent incidents had occurred at various showings during screenings of number of 1979 gang movies such as Die Warriors (1979), The Wanderers: Terror in der Bronx (1979) and Boulevard des Todes (1979).
Director Richard Linklater has said Wut im Bauch (1979) influenced his film Confusion - Sommer der Ausgeflippten (1993). Wut im Bauch (1979) also partly inspired the music videos for the songs "Smells Like Teen Spirit" by Nirvana and "Evil Eye" by Fu Manchu.
While director Jonathan Kaplan was in New York casting the main roles, writers Charles S. Haas and Tim Hunter were in Colorado, looking for local kids to fill out the cast's minor parts and extras. When they would visit local high schools to recruit talent, the schools tended to bring them to the students involved in their drama clubs and plays, who did not fit the mold of the troubled youth in the movie. Instead, Haas and Hunter looked for, in Haas' words, "the kids getting stoned out on the hill behind the school," and they even went to special schools for problem students to hunt for the kids who appear in the film.