The Czech Social Democratic Party (Czech: Česká strana sociálné demokratická) is a political party in the Czech Republic. It is the largest single party in the lower house of the Czech Parliament, with 70 of 200 representatives. It governs in a coalition with two smaller parties, the Christian and Democratic Union - Czechoslovak People's Party, and the Freedom Union.

See also: Politics of the Czech Republic, List of political parties in the Czech Republic.