The acronym ISA may refer to:
- Information sharing architecture
- Instruction set architecture
- Intelligence Services Act 1994 (U.K.)
- Intelligence Services Act 2001 (Australia)
- Intelligent Speed Adaptation
- Interconnection Security Agreement
- International Society of Automation (formerly the Instrumentation, Systems, and Automation Society)
- Interoperability Solutions for European Public Administrations
- Interoperability solutions and common frameworks for European public administrations, business and citizens