TLA is a three-letter abbreviation which can mean several things. Most commonly, it literally means three-letter abbreviation or three-letter acronym, or occasionally Three letter agency.

Other meanings include:

In New Zealand, Territorial local authority

At least four organizations

• Theater Libraries Association
• Thai Libraries Association in Thailand
• Texas Libraries Association in Texas, USA
• Tennessee Library Association in Tennessee, USA
• Technology Leadership Academy in Missouri, USA
• Texas Locksmiths Association
• Tasmanian Logging Association

Some technical terms

• Telemetry link adapter
• Telephone line adapter
• Thin layer activation
• Temporal Logic of Actions (see also Temporal logic)

• In US military usage, Travel Lodging Allowance
• Tom Lord's Arch (http://regexps.srparish.net/www/#Gnu-arch), an implementation of the GNU Arch revision control system