(IWW), revolutionary industrial union organized in Chicago in 1905 by delegates from the Western Federation of Mines, which formed the nucleus of the IWW, and 42 other labor organizations. It became the chief organization in the United States representing the doctrines of syndicalism. Leaders included Eugene V. Debs, William D. Haywood, and Daniel De Leon. Its members were called, among other nicknames, the Wobblies.
The aim of the IWW was to unite in one body all skilled and unskilled workers for the purpose of overthrowing capitalism and rebuilding society on a socialistic basis. Its methods were direct action, propaganda, the boycott, and the strike; it was opposed to sabotage, to arbitration or collective bargaining, and to political affiliation and intervention. The organization spread to Canada and Australia and in a very small way to Europe, but its main activities were confined to the United States. It was especially strong in the lumber camps of the Northwest, among dockworkers in port cities, in the wheat fields of the central states, and in textile and mining areas. Of the 150 strikes conducted by the IWW, the most notable occurred at Goldfield, Nev. (miners, 1906–7); at Lawrence, Mass. (textile workers, 1912); at Paterson, N.J. (silk workers, 1913); in the Mesabi range, Minn. (iron miners, 1916); in the lumber camps of the Northwest (1917); at Seattle (general strike, 1919); and in Colorado (miners, 1927–28).
The IWW's stand against political action led to controversy among the members, with De Leon emphasizing the Marxist point of view as against those opposing political action. De Leon and his followers were expelled in 1908 and set up an independent organization, which was never more than a splinter group and was dissolved in 1925. In 1924 a split took place in the parent organization between the Westerners and the Easterners over the question of centralization.
At the time of World War I the IWW was antimilitaristic; its members were accused of draft evasion, of fomenting German-paid strikes in order to cripple essential war industries; of sabotage; and of criminal syndicalism. Many of its leaders and members were thrown into jail. Adding to the union's troubles was the fact that a great portion of the membership was made up of migratory and casual laborers, and it was difficult to organize them into a cohesive group. From a probable strength of at least 30,000 in 1912, the membership fell to less than 10,000 in 1930 and in the mid-1990s was less than 1,000.