(2022-WAFA) : For foreign people : WELCOME TO FRANCE

• If you're living in Paris (and by “Paris” I mean arrondissements related to the prefecture of Paris), SU will take in charge the “creation” and the “renewal” of your “titre de séjour” (visa). It's not automatic you should ask for it at the Zamansky Tower when you sign your contract. You might have to send documents to them, and then pick up the titre from the Prefecture of Paris.
• If not ! Sad but true, you should make the trip yourself. So, you start by asking for a “convention d'accueil” from SU. To get this paper you should full fill and sign (with the supervisor (for phD) and the lab director) a form. Send it to the responsible at the zamansky tower.Once you have this paper you should look for the prefecture related to your adress. Read careffully what is in their website (use the official website “.gouv”). From my personal experience in 2018 (before COVID) I went myself with all the documents they asked for (contract, convention d'accueil, Diploma, passeport, old visa, photos, forms from the website etc.). But in 2022 and after the COVID they created a plateform were you can submit all the papers. You will be contacted by SMS to informe you that your “titre de séjour” is ready and you should pay for it.
• Update (Sharbat): From 2021, those who are applying for the first time under the 'passeport talent' scheme - most of the applications are now done online with no need of visiting anyone before you go to pick up the titre. The website of https://administration-etrangers-en-france.interieur.gouv.fr/ will be your friend.