CLN may refer to:
In computing and technology
- Class Library for Numbers, a free software project
- CLN (technology), Cheng Low NOx Emission Control Technology
- Computer Learning Network, a technical school (college) in Mechanicsburg, Pennsylvania
In politics and government:
- Certificate of Loss of Nationality, an American form
- Comitato di Liberazione Nazionale, the underground political entity of Italian Partisans during the German occupation of Italy
In other fields:
- City Light News, a Christian monthly newspaper
- abbreviation for Chapeltown railway station, in South Yorkshire
- Credit-linked note, a security issued by a special purpose company or trust
- Sri Lanka's International Telecommunications Union abbreviation