Sociedade União 1º Dezembro is a sports club from Sintra, Portugal. The football section of the club was founded on 6 April 1938, the women's football section in 1995. The men's football team plays in the Campeonato de Portugal.
The Campo Conde de Sucena (meaning in English "Count of Sucena Field") is located within the Count of Sucena Sports Complex in Sintra. It is a football stadium with capacity for 1,000 spectators and is the home of the S.U. 1º Dezembro club.
