In 1921, Bund-affiliated trade unions joined the Central Commission of Class Trade Unions (Polish: Komisja Centralna Zwiazków Zawodowych—KCZZ), the governing council of the Union of Professional Associations (Polish: Związek Stowarzyszeń Zawodowych—ZSZ), the umbrella organization of the Polish Socialist Party trade unions. However, while part of the KCZZ, the Bund unions were not part of the ZSZ.[7][8]