The Sejm Library collects at present :
- library materials,
- archival documents (Sejm Archives),
- museum exhibits (Museum Division).
Collections of library materials (December, 31 2015 – 538 935 units) consist of two physically separate parts, each of them of different origin and character, and held in a different locations.
The first one – the main library collection – consists of materials related to the principal function of the Sejm Library as a parliamentary library, which have been collected since its beginning.
The core of the second part consists of the library collection of the former Archives of the Polish Left (previously: the Central Archives of the Central Committee of the Polish United Workers’ Party), which was incorporated into the Sejm Library in 1991. Access to it is at present provided at the Social History Collection Division.