The XVII Constitutional Government of Portugal was the 17th government of the Third Portuguese Republic, under the Portuguese Constitution of 1976. It was in office from 12 March 2005 to 26 October 2009, and was formed by the members of the Socialist Party (PS). José Sócrates, leader of the PS, served as Prime Minister.

The Socialist Party is a social-democratic political party in Portugal. It was founded on 19 April 1973 in the German city of Bad Münstereifel by militants who were at the time with the Portuguese Socialist Action. The PS is a member of the Socialist International, Progressive Alliance and Party of European Socialists, and has nine members in the European Parliament within the Progressive Alliance of Socialists and Democrats group during the 9th European Parliament. It was the governing party of Portugal between November 2015 and April 2024, subsequently winning the 2019 and 2022 legislative elections.