William Z. Foster (1881-1961), born in Taunton, Mass., was a member of the Socialist Party of America from 1901 to 1909, joined the United Wage Workers' Party of Washington in 1909, and became a member of the IWW in 1910, participating in the Spokane free-speech campaign. He then traveled to Europe, where he became a convert to the strategy of "boring from within" existing trade unions.

After unsuccessfully contesting the AFL's right to represent the American labor movement at the 1911 meeting of the International Secretariat in Budapest, Foster returned to the United States and settled in Chicago. He left the IWW in 1912, joined the Brotherhood of Railway Carmen of America, and subsequently organized the Syndicalist League of North America and the International Trade Union Educational League.

Between 1917 and 1919 Foster led AFL organizing campaigns in the packinghouse and steel industries, and in 1920 he founded the Trade Union Educational League. The following year he went to Moscow and, upon his return, joined the American Communist party.

Foster was the party's candidate for president in 1924, 1928, and 1932 and served as the party's longtime chairman (1930?-44, 1945-57) and chairman emeritus (1957-61). He died in Moscow, where he had gone for medical care.