The Sejm Library offers four catalogue databases:

• Library main catalogue - the main catalogue database, containing descriptions of all books acquired to the main collection after 1978, to the Social History Collection (ZHS) Division after 1993 as well as selected books of the earlier period. The database may be searched by some elements of formal description (author, title, series, etc.) as well as by elements of subject description (thesaurus terms and subject headings).
• Scanned card catalogue of the library main collection - the catalogue of older part of the main collection (books acquired before 1979). It contains digital copies of cards from the traditional catalogue and with the indexes of authors, titles and call numbers.
• Scanned card catalogue of the ZHS collection - the catalogue of older part of the ZHS Division collection (books acquired before 1994). It contains digital copies of cards from the traditional catalogue and with the indexes of authors, titles and call numbers.
• Early printed books - the catalogue of early printed books (issued before 1801) from the Sejm Library's main collection as well as from the Museum Division. The database may be searched by selected elements of formal description: titles, authors, publishers, printers, etc.

For books published after 1800, it is recommended to start searching for any books (regardless of the year of publication) in the Library main catalogue – and only when it fails, proceed to Scanned card catalogues.

Library main catalogue contains descriptions of:

• Polish and foreign parliamentary publications,
• Polish and foreign official publications,
• periodicals and international organizations publications that were acquired by the Sejm Library after 1993.

The works on retrospective conversion of serials are still being conducted by the Library.