This paper describes the process of retroconversion in the Jagiellonian Library in the course of the last fifteen years. It offers an insight into the history of the methods used for retrospective catalogue conversion in the period before the Section of Retrospective Cataloguing had been established. This Section started its activity in the year 2008 as a part of the Department of Book Cataloguing. The paper analyzes the tasks which are currently undertaken by this Section; it describes the methods of work as well as various projects thanks to which the Jagiellonian Library has received financial support. The authors of this paper have also suggested return into the debate about a national program of retroconversion, for which the project, known as "NUKAT - Highway of Digital Information" - administered by the Warsaw University Library - could be a good reason.