Between 1917 and 1939 the Library of the 'Ministerstwo Wyznan Religijnych i Oswiecenia Publicznego' (The Ministry of Religious Denominations and Public Enlightenment - MRDPE) in Warsaw served as the central pedagogical library of the Second Republic of Poland. Drawing on valuable though incomplete archive and printed sources, the present article examines the origins, organisation and activities of the Library established together with the Department of Religious Denominations and Public Enlightenment in 1917. Initially, its main task was to support the work of ministry officials, later also of other people professionally associated with the education sector. With time, it began to play an increasingly important role in popularising the achievements of pedagogy and related disciplines, as well as in the self-education and research work of teachers and other professions. The history of the Library is presented against the background of transformations taking place at the MRDPE in the inter-war period. For the Library, although autonomous to some extent, was from the very beginning an integral part of the MRDPE, therefore, any changes in the organisational structure of the Ministry determined its functioning.