Established in Paris in 1900; had its office in Brussels; provided the Second International with a permanent organizational structure; organized its congresses and conferences; president was Emile Vandervelde from 1900; Camille Huysmans was its secretary from 1905 and tried to maintain the BSI's international contacts from his Dutch exile after the International's collapse with the outbreak of the First World War.

Microfilms donated to the IISH by the École de Hautes Études en Sciences Sociales, Centre d'Études sur l'URSS, Paris in 1979, see Annual report IISH 1979, p. 36.

Microfilms and prints of microfilms of a part of the papers of Camille Huysmans. Correspondence with affiliated parties, other organizations and persons, including letters from Hjalmar Branting, Arthur Henderson, Constantino Lazzari, Thorwald Stauning, Pieter J. Troelstra, Emile Vandervelde and others; agenda of correspondence of the Bureau 1914-1917, 1919; documents on conferences 1915-1920; circulars to the affiliated parties 1914-1915; file on the deportation of Belgian workers 1916-1917.

List made by Jack Hofman in 1985

Microfilms 1967

7 microfilms

Originals in the Camille Huysmans papers at the Archief en Museum voor het Vlaams Cultuurleven, Antwerp, Belgium