Director Denis Villeneuve was disappointed with his first two movies, Un 32 août sur terre (1998) and Maelström (2000), so he took a nine-year sabbatical as a stay-at-home dad. He vowed to return "when I was ready to make a film I could be proud of", which was Polytechnique (2009).
The movie was screened for the family members of the victims before being released commercially. The film was released with their blessing.
The film was shot in black and white in order to avoid the presence of blood on screen.
The name of the perpetrator is never once mentioned in the film.
Filmed simultaneously in English and French.