The IISH was founded in the turbulent 1930s at a time when, following Hitler's seizure of power, many documents and archives of opposition movements were threatened with becoming irredeemably lost. Vital archives that were brought to safety in Amsterdam in the early years include: the archive of the German socialist movement (including the manuscripts of Marx and Engels), the archives of revolutionaries at risk from Stalin, and the archives of the Spanish trade unions, threatened with falling into Franco's hands.
After the end of World War Two, the IISH successfully continued collecting documents. With the exception of Dutch emancipation movements such as Provo, and internationally active movements such as Greenpeace and Amnesty International, endangered archives of organizations and individuals from countries like Turkey, Iran, Burma and Indonesia were safely housed at the Institute.
The total archival collection measures over 5,400 collections, almost 18 kilometer. Archives and archival finding aids may be searched on this website (or in the catalogue). Descriptions of Dutch archives are in Dutch, the other ones are in English. IISH’s leading archives are fully available to view online.