The article indexes and describes Ksawery Działyński’s (1756–1819) book collection. Ksawery developed his library on the basis of the collection he inherited from his predecessors, subsequently buying further items. The collection comprised a total of about 650 works. The turn of the 19th century was the time when the so-called “national book collections” were developed in the Polish lands with a view to the rescuing of Polish library resources. However, an analysis of Ksawery’s stock provides evidence that, being a politically engaged patriot, he collected his books in the spirit of the Enlightenment. Most of the books in the collection are French volumes (77%) and they mainly represent literature, history and history of art, and to a smaller extent science, medicine, and agriculture. The books were to help their owner conduct his political activity and manage his estate, and to provide entertainment. The collection was primarily developed for Ksawery’s own purposes.