The National Library (Polish: Biblioteka Narodowa, BN) is the national library of Poland, subject directly to the Polish Ministry of Culture and National Heritage. The main seat of the National Library is located in the Ochota district of Warsaw, adjacent to the Mokotów Field. It is one of the oldest cultural institutions in Poland, established as Załuski Library in 1732, which ultimately evolved into the National Library of Poland reactivated in 1928.

The library collects books, journals, electronic and audiovisual publications published in the territory of Poland, as well as Polonica published abroad. It is the most important humanities research library, the main archive of Polish writing and the state centre of bibliographic information about books. It also plays a significant role as a research facility and is an important methodological center for other Polish libraries.

The National Library was one of the first libraries in Europe that fulfilled the tasks of a modern national library in developing collections covering the entire body of Polish literature and making available to the public.

Literature and making those works accessible to the public receives a copy of every book published in Poland as legal deposit. The Jagiellonian Library is the only other library in Poland to have a national library status.

There are three general sections:

The National Library's history has origins in the 18th century (Załuski Library) including items from the collections of John III Sobieski which were obtained from his grand daughter Maria Karolina Sobieska, Duchess of Bouillon. However, the Załuski collection was confiscated by troops of Russian tsarina Catherine II in the aftermath of the second Partition of Poland and sent to Saint Petersburg, where the books formed the mass of the Imperial Public Library on its formation in 1795. Parts of the collection were damaged or destroyed as they were mishandled while being removed from the library and transported to Russia, and many were stolen. According to the historian Joachim Lelewel, the Zaluskis' books, "could be bought at Grodno by the basket".

Because of that, when Poland regained her independence in 1918, there was no central institution to serve in the capacity of a national library. On 24 February 1928, by the decree of president Ignacy Mościcki, the National Library was created in its modern form. It was opened in 1930 and initially had 200 thousand volumes. Its first Director General was Stefan Demby, succeeded in 1934 by Stefan Vrtel-Wierczyński. The collections of the library were rapidly extended. For instance, in 1932 president Mościcki donated all of the books and manuscripts from the Wilanów Palace Museum to the library, some 40 thousand volumes and 20 thousand pictures from the collection of Stanisław Kostka Potocki.

Initially the National Library lacked a seat of its own. Because of that, the collections had to be accommodated in several places. The main reading room was located in the newly built library building of the Warsaw School of Economics. In 1935 the Potocki Palace in Warsaw became home for the special collections. A new, purpose-built building for the library was planned in what is now the Mokotów Field, in a planned monumental "Government District". However, its construction was hampered by the outbreak of World War II.