 Established as Grupo Desportivo da CUF Lisboa (CUF Lisboa, with CUF standing for the company Companhia União Fabril) in 1937, it was one of three football clubs created by the parent company, whose players were also workers (the other clubs were CUF Barreiro, founded in 1937 and the most successful of the three, and the short-lived CUF Porto that existed between 1945 and 1950).In 1940, the Estado Novo forced the club to change its name, as it didn't allow sports teams with corporate names.Thus the club changed its name to "Clube de Futebol Os Unidos" or "Unidos de Lisboa" (CUF Barreiro, meanwhile changed to "Unidos Futebol Clube" or "Unidos do Barreiro").