Thomas Lilti chose to show a normal junior high school, neither elite nor in trouble, to focus on the teacher's job.
Writer/director Thomas Lilti cast many actors he has already worked with in this movie, most notably Vincent Lacoste from Hippocrate (2014), François Cluzet from Médecin de campagne (2016) and William Lebghil from Première année (2018).
For the music, many options were considered, including no music at all for the whole movie. In the end, Jonathan Morali was chosen to compose a few tracks to tie the movie together.
For the final scene, Thomas Lilti struggled to find the right song, and then remembered a cover of "Le temps des muguets" made for Première année (2018), sung by Vincent Lacoste and William Lebghil, for a scene which ended up on the cutting floor, and thought it made perfect sense for the ending of Un métier sérieux (2023).
Thomas Lilti wanted to give as much space as possible to the actors, and thus opted for long takes. The discipline hearing scene ended up lasting 40 minutes without breaks, which proved very physical for the boom operators.
The movie was shot in March and April 2022 around Paris.