Democratic Union of Catalonia

The Democratic Union of Catalonia (Catalan: Unió Democràtica de Catalunya; IPA: [uniˈo ðəmuˈkɾatikə ðə kətəˈluɲə], UDC), frequently shortened as Union (Catalan: Unió; IPA: [uniˈo]), was a regionalist, Christian-democratic political party in the Catalonia region of Spain existing between 1931 and 2017. Together with Democratic Convergence of Catalonia (CDC), they formed the Convergence and Union (CiU) alliance and federation from 1978 until its dissolution in 2015, under which they would rule the government of Catalonia for almost three decades during the recent Spanish democratic period.

It described itself as Catalan nationalist and Christian-democratic and was a member of the European People's Party (EPP). It advocated for centrist and moderate Catalanism without explicitly renouncing independence, aiming for the constitution of a confederal state in Spain made up of sovereign entities (including Catalonia) that could become independent but rejecting unilateralism as a viable political philosophy.

After the breakup of CiU, a party split that took away half of its membership, and UDC's failure in securing parliamentary representation in the 2015 Catalan and Spanish general elections, the party's mounting debts brought it to bankruptcy, leading to its dissolution on 24 March 2017.