In September 2001, the National Library of Tunisia began the retrospective conversion of its catalogues established before 1998. Indeed, since 1998 new purchases were catalogued in a temporary database using the software CDS/ISIS. The main classifications of the National Library of Tunisia catalogues are both chronological and linguistic: catalogues before 1966/after 1966; Arabic collections/foreign collections. The mobilization of a team and a project manager in the National Library, assisted during the starting up phase by a French chief librarian, allowed the effective launching of the operation in April 2002, with the help of two temporary teams recruited to enter data. Retrospective conversion will continue till December 2008. So, by relying on its own resources, while obtaining significant budget allocations for the temporary teams and the computer management of the project, the National Library managed to lead this great operation. With very reasonable means, but a strong will of its management and its staff, and a lot of inventiveness, the National Library of Tunisia has well advanced in the retrospective conversion of its catalogues. There is certainly more work to be done, not only concerning data entering, but also conception, particularly for the Arabic part. Thanks to the retrospective conversion the National Library of Tunisia will eventually have a multilingual unique catalogue where the old and new documents will be indicated, which will make scholarly research on printed material, communication and conservation much easier Finally the new building, which will soon house the printed and manuscript collections, should endow the institution with great national prestige, whereas new technologies accompanying the retrospective conversion will expand its international audience. [ABSTRACT FROM AUTHOR]