LTI can refer to:
- LTI - Lingua Tertii Imperii, a book by Victor Klemperer
- Language Technologies Institute, a division of Carnegie Mellon University, Pittsburgh.
- Language Testing International, a language testing company delivering ACTFL certified tests, White Plains, NY.
- Learning Tools Interoperability, a standard way of integrating rich learning applications (often remotely hosted and provided through third-party services) with platforms like learning management systems, portals, or other educational environments. Developed by the IMS Global Learning Consortium.
- LTI system theory (linear time-invariant system theory), an engineering theory that investigates the response of a linear, time-invariant system to an arbitrary input signal
- London Taxis International, a division of Manganese Bronze Holdings PLC
- License to Ill the debut album by Rap Group Beastie Boys
- Lost Time Incident
- LTI Software & Engineering, a Canadian-based consulting firm in information technology (IT) and engineering