The Amalgamated Society of Woodworkers (ASW) was a British trade union representing carpenters, joiners and allied trades. The ASW was formed in 1921 by the amalgamation of two smaller unions. It was itself merged into the Union of Construction, Allied Trades and Technicians in 1971.
The ASW was formed in 1921 through the merger of two rival unions: the Amalgamated Society of Carpenters, Cabinetmakers and Joiners and the General Union of Carpenters and Joiners. In 1922, most of its Irish members left to form the Irish National Union of Woodworkers.
The ASW had 176,000 members by 1945, making it the seventh largest union in Britain. Its membership rose to 198,000 by 1956. In 1965, the National Union of Packing Case Makers (Wood and Tin), Box Makers, Sawyers and Mill Workers merged into the ASW.
On 1 July 1970 the ASW was merged with Amalgamated Society of Painters and Decorators and the Association of Building Technicians to form the Amalgamated Society of Woodworkers and Painters. One year later the new union was itself merged with Amalgamated Union of Building Trade Workers to become the Amalgamated Society of Woodworkers Painters and Builders (ASWPB). At the end of 1971 the ASWPB was renamed the Union of Construction, Allied Trades and Technicians (UCATT).
The union sponsored a large number of Labour Party candidates, many of whom won election.