Organizations
- Party of the Democratic Left (Slovakia), a former political party of Slovakia (1990–2004)
- Party of the Democratic Left (2005), a centre-left political party in Slovakia founded 2005
- Scottish Defence League, a far-right anti-Muslim street protest organisation in Scotland
- Social Democratic League of America (1917-1920), an American propaganda organization
- Soqosoqo Duavata ni Lewenivanua, a political party in Fiji
- Space Dynamics Laboratory, at Utah State University
- SDL International, a British company selling translation tools and services
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