The Movement of Social Democrats (French: Mouvement des Démocrates Socialistes; Arabic: حركة الديمقراطيين الاشتراكيين, Hizb al-Dimocratiyin al-Ishtirakiyin) is an opposition political party in Tunisia. It is the second-largest party in the Chamber of Deputies, behind the dominant Constitutional Democratic Rally, with sixteen seats.
In 1999, it became the largest opposition party, with 13 seats in the Tunisian parliament. In 2001, the then-party leader Mohamed al Mouadda was charged with having formed a pact with the banned Islamist group Al Nahda. At the 2004 parliamentary election, the party won 4.6% of the popular vote and 14 seats. Their number of seats rose to 16 at the 2009 election.