Sociedade União 1º de Dezembro is a sports club from Sintra, Portugal. The football section of the club was founded on 6 April 1938 and the women's football section in 1995. The women's football team play in the top national league, the Campeonato Nacional de Futebol Feminino and have been the dominant force of the last decade. After the first league title in 1999-2000, the team won every league title from the 2001-02 season until 2011-12. The team has also won 7 Portuguese Cups ever since the creation of the competition in 2003-04. It is currently the most successful women's football team in Portugal.
The women's football section of the Sociedade União 1º de Dezembro was created in 1995, making the club one of the few in Portugal to have both a men's and a women's football team. Ever since the creation of the section, the team have won 12 league titles - 11 of which in a row - and 7 Portuguese Cups making it the most successful women's football team in Portugal.
After a 3rd place in the 2012-13 league, the women's football section was incorporated into Sevenfoot, a non-profit association managing the youth football teams of the club. This restructuring involved several players of the main team leaving the club, changing the manager and making the U-18 team into a 7-a-side team to challenge for the new Lisbon U-18 Regional League.