The International Institute of Social History (IISH) was officially established on November 25, 1935, but its history goes back to the 1920s. In 1914, Nicolaas W. Posthumus (1880-1960), who ranked among the pioneers of modern economic history in the Netherlands had set up the Netherlands Economic History Archive (NEHA), the first of a series of scholarly institutions he initiated. The NEHA concentrated on the preservation of archives of companies and related organizations, and on the collection of other sources relevant to economic history.