The collection is dedicated to the history of the Brest Church Union of 1596. It contains documents covering more than five centuries of the history of Belarus - from the mid-80s of the XIV century. to the 40s. XIX century. For the first time, this unique publication comprehensively presents documents revealing the prerequisites, reasons, adoption and evolution of the church union. Many of the published documents have long since become bibliographic rarities. The publication is intended for specialists in the field of civil and church history, the history of socio-political thought, graduate students and students of humanitarian faculties and universities, as well as for everyone who is interested in the history of their Fatherland.