In the Second Republic of Poland special libraries described as teacher and/or pedagogical libraries played a crucial part in teachers' formation, specialist training and in popularising the achievements of pedagogics and related sciences. So far those institutions have not been a subject of in-depth research, while the functions they had within the education system make it worth trying to reconstruct their history and to analyse their work thoroughly. National, regional and local source materials can be of great help here; these materials are preserved in the Modern Records Archives (Archiwum Akt Nowych) in Warsaw, the State Archives of the Brest District in Brest (Belarus), the Lithuanian Central State Archives in Vilnius and the Central State Archives of Historical Records of Ukraine in Lviv. Since the functioning of pedagogical libraries is very closely connected with such issues as teacher training, the primary research in the above mentioned institutions covered first of all the records of school authorities of the III, II and I level, that is, the Ministry of Religious Denominations and Public Enlightenment, superintendents of school districts, including the Lviv, Brest and Vilnius districts, as well as school inspectorates operating in those districts between 1918 and 1939. The current research has revealed valuable source materials; despite the fact that they are incomplete, they can still help us characterise the institutions that constituted the network of teacher libraries. In addition, these materials make it possible for us to reconstruct the fate of the best organised pedagogical libraries, i.e. the Library of the Ministry of Religious Denominations and Public Enlightenment and those libraries that belonged to district school inspectorates. They also allow us to verify certain hypotheses concerning the functioning of libraries for teachers. We have to remember, however, that in order to construct a relatively complete source base – that can be helpful in carrying out a reliable, well-documented study on teacher libraries in the Second Republic of Poland - we have to take into account not only archive materials but also printed sources.