ENThe majority of enclosed convents were seated in the eastern areas of the historical Nobles' Commonwealth. Each of the rules and monastic constitutions put emphasis on the significance of liturgy and lectio divina - spiritual reading in the life of the community. Book collections presented the development of intellectual culture in the convents; these book collections were at the same time an indication of the level and quality of a convent, constituted a subscribed and realized system of monastic values and were associated with the spirituality of the times. The article presents the rules of organization of libraries, especially the planned decentralization of collections, problems of collecting, studying, and storage, as well as their content resources. Special attention was paid to the history of book collection, with emphasis of annulments on their scattering and destruction.