The article presents the preparations and implementation of the 2017–2018 retroconversion programme, ordered by the Director of State Archives for implementation in all archives of the state archive network, in the largest of these archives, i.e. the State Archive in Warsaw. The author of the article is also a Programme coordinator and presents the Programme against the background of the inner workings of the Archive in 2017 and the guidelines of the State Archives Director. She analyses the adopted principles and rules and the multifarious methods of retroconversion employed. The author presents the complications which arose due to the size of the institution, the character of the finding aids used and the incomplete access to fonds. The author also paints a picture of the doubts and questions which accompanied the decisions made regarding the scope of the project in order to present, in addition to the obvious advantages offered by an electronic registry system, other advantages which set the course for further work on the fonds.