The Social Democratic Party (abbreviated SDP) is a political party in the Southern Arc Islands. It is currently one of the largest parties in both the First and Second Chambers. Its current leader/chairman is Warwick Samuelson, who was formerly the Prime Minister. The current President, Victor Sheraldin, is affiliated with the party.

The SDP generally takes a (centre-)left standpoint. It was founded in 2004 by members of the Labour Party who were discontent with that party's rightward movement in the manner of Tony Blair's New Labour movement in the United Kingdom.