[2] The library opened in 1933, and is located at 37a Clerkenwell Green, formerly home to many radical organisations and base of an important publishing operation.

[3][4] The library's collection comprises over 60,000 books, pamphlets, items, and newspapers on Marxism, socialism, and working class history.

Part of it was occupied from 1872 onwards by the radical London Patriotic Society; and from 1893 (with the financial backing of William Morris) by the Twentieth Century Press Ltd, publishers of Justice, the newspaper of the Social Democratic Federation.

The library features the fresco The worker of the future upsetting the economic chaos of the present, painted by Jack Hastings in 1935 with the assistance of the American artist, Clifford Wight.

[8] Through these changes of use, the fabric had undergone numerous alterations and dilapidations, and in 1968–1969 the building underwent a major programme of work to restore the 18th-century appearance of the front.