The IISH has a unique and manifold collection of Yiddish material consisting of books, brochures, periodicals and pamphlets of the early Jewish socialist and anarchist movement in Eastern and Western Europe.
In addition to this printed material the Institute has a large collection of Bundist (election) posters, photo's and prints, mainly from interbellum Poland.
Next to this printed and visual material the IISH owns part of the Bund-archives viz. the incoming material from the Bund Foreign Committee in Geneva as well as material from the Central Office of the Bund in Geneva. Yiddish-language letters in various archives at the IISH have been made accessible through a database.
The IISH acquired the Bund archive in 1935, most of the other Yiddish material comes from the collections of Max Nettlau, Pierre Ramus and Rudolph Rocker.
Though the Bund archive was the first acquisition of the IISH after its foundation in 1935 this collection, as well as the the other Yiddish material had to wait for the expertise and dedication of prof. dr R. Fuks-Mansfeld (1930-2012) to be properly catalogued and arranged. The IISH now has one of the largest accessible collections in this field.