The book is dedicated to a unique historical phenomenon - the movement of Orthodox church brotherhoods that existed on Ukrainian-Belarusian lands at the end of the 16th - first half of the 17th centuries. The sources of the emergence of brotherhoods, their plans for the reorganization of the Kyiv metropolis, as well as contacts between clergy and laity in the eastern lands of the Commonwealth, in particular, the confrontation between the episcopate and the leaders of the fraternal movement at the end of the 16th century, are considered.