William F. "Bill" Kruse (1894–1979) was an important head of the Young People's Socialist League (YPSL) in the 1910s. He was a member of the Socialist Party of America until 1921, acting as a leader of the party's Left Wing faction, loyal to the Third International (Comintern). Thereafter he joined the Workers Party of America, serving as Assistant Executive Secretary of the WPA from the time of its foundation in December 1921.
William F. "Bill" Kruse was born in Hoboken, New Jersey to German and Danish immigrant parents in 1894.
Kruse worked briefly as a sheet metal worker in his youth. He later studied at the Socialist Party of America's Rand School of Social Science under Algernon Lee.
In July 1915, the governing National Executive Committee of the SPA appointed the 21-year-old as Director of the party's youth section, the Young People's Socialist League (YPSL). Kruse served two terms in this position, finishing in June 1918. He also served as editor of the YPSL's national publication, Young Socialists' Magazine, from 1918 to 1919 and as the Provisional Secretary of the SPA's national Socialist Sunday School movement.
Kruse was the fraternal delegate of the YPSL to the party's seminal 1917 Emergency National Convention in St. Louis. Militantly opposed to the war in Europe, Kruse, a law school graduate, worked to defend the civil rights of war opponents as a leader of the American Liberty Defense League.
As head of the Socialist Party's youth organization and a vociferous critic of American participation in the war, Kruse was targeted by the US Department of Justice headed by Attorney General A. Mitchell Palmer under the Espionage Act. Kruse was indicted in Chicago by a grand jury on Feb. 2, 1918, and the secret indictment was made public on March 9. The sensational and widely publicized trial of Kruse and 4 other top members of the Socialist Party began before Judge Kenesaw Mountain Landis on Dec. 6, 1918. This trial ended Jan. 4, 1919, with the jury finding Kruse and his associates (Victor L. Berger, Adolph Germer, J. Louis Engdahl, Irwin St. John Tucker) guilty. Landis sentenced each to 20 years in the Federal penitentiary, a sentence which was appealed and later overturned on the basis of judicial bias.