The Union of Trade Unions (Polish: Związek Związków Zawodowych, ZZZ) was a trade union confederation formed as a result of an attempt to unite pro-social trade unions. It operated until 1939 and was one of the three largest union centers in Poland. It was pro-government at first, but under the influence of anarchists, it began to lean towards anarcho-syndicalism from 1936 onward. Soon it became the target of police and judicial repression, and their efforts were finally interrupted by the outbreak of World War II.