The authors of the article attempt to present current research into the "Brest Catechism", the sixteenth-century text reprinted in 1908 and edited by Franciszek Pułaski as part of the Collectanea Series by the Krasiński Estate Library. It was prefaced by Pułaski, and reviewed by Aleksander Woyde and Aleksander Brückner. The article presents background to the publication of the Catechism, i.e. the activity of Mikołaj “the Black” Radziwiłł, specifically setting up the printing house in Brest in 1553 and engaging Bernard Wojewódka in it. The authors also attempt to establish the reasons for the Catechism’s dual composition.