SLF is a three-letter abbreviation with multiple meanings:
- Superleague Formula, a motorsport racing series
- Subscriber Location Function, an entity in IP Multimedia Subsystem (IMS)
- Seattle Liberation Front, a radical anti-Vietnam War organization
- Shuttle Landing Facility, the primary landing site for the Space Shuttle
- Stephen Lewis Foundation, a foundation helping with HIV/AIDS
- Stiff Little Fingers, a Northern Irish punk band
- Sun Life Financial, a leading international financial services company
- Super low frequency, a region of the electromagnetic spectrum between 30 hertz and 300 hertz
- Superior longitudinal fascicle, a part of the brain
- Self-loading freight, a derogatory term for economy class passengers