Bel Kaufman, in the Preface to the 25th anniversary edition of the book, writes: "The movie was filmed in New York City, in and around Haaren High School, which had been emptied for the summer."
Bel Kaufman, the author of the book on which this movie was based, appeared as an extra in the movie, and served as a technical advisor.
Bel Kaufman's original description of Sylvia Barrett was closer to that of Audrey Hepburn.
Film debut of Bud Cort, in an uncredited walk-on role as a student. He is seen at the tail end of the film, chewing gum and tossing a book in the air as he passes by Sandy Dennis in the school hallway.
Like Dangerous Minds 28 years later, this movie was filmed in a real-life urban high school building, using real high school kids from the neighborhood as extras, many of whom were believed to be armed on the set.
Puerto Rican author Esmeralda Santiago has a small role as a student, this was her film debut and her only film role. Her experiences from working on the film are highlighted in her book "Almost a Woman" (see also: Almost a Woman).
The U.S. State Department submitted this film to the 1967 Moscow Film Festival, in order to contradict Soviet propaganda, which implied that all American schools were racially segregated.
The winter scenes were filmed on a hot day in August 1966.
This movie was filmed in a real live New York City school building. While many people claim that it was filmed in Hell's Kitchen at John Jay College, several landmarks suggest that it was filmed in El Barrio, a section of Manhattan near Spanish Harlem, at J.H.S. #99.