Using archived documentation, reporting in particular on the decisions made by the Association at the Plenary Assembly and in the Librarians’ Assemblies, the contribution retraces the various training procedures involving libraries and the staff responsible. From 1994 to 2023, decisive steps have been taken: from the paper file and the Vatican regulations to MARC 21, to RDA and the realisation of the Parsifal platform, to the shared catalogue. This process was made possible by continued cooperation and decisions made together; these decisions led to tangible training projects for librarians and, in particular, to specific courses planned for cataloguers.