Isa or ISA may refer to:

• Mount Isa, Queensland, Australia, a city
  • Mount Isa Airport, IATA airport code "ISA", airport serving the city
• Isa Town, middle class town located in Bahrain
• Isa (river), a river in Belarus
• Isa, Kagoshima, Japan, a city
  • Isa District, Kagoshima, former district in Japan, equivalent to the current city
• Isa, Nigeria
• Isa, Amur Oblast, Russia

• Īsā, the name of Jesus in Islam
• Isa (name), an Arabic name corresponding to Jesus in English
• Isa, stage name of Lee Chae-young, member of K-Pop group STAYC
• Isa, female given name, short for Isabel or similar names beginning with Isa- such as Isadora
• Isa Maud Ilsen (1868–1937), Canadian-American music therapist, nurse, lecturer
• Isa Tengblad (born 1998), Swedish singer using the mononym Isa
• Juan Isa (1913–1993), president of the International Baseball Federation (FIBA) from 1969 to 1975
• İsa Aras Mersinli, perpetrator of the 2026 Onikişubat school shooting

• ISA (Days of Our Lives), spy agency in a TV series
• Isa the iguana, in TV series Dora the Explorer
• Interplanetary Strategic Alliance (ISA), military alliance in videogame saga Killzone

• Isa (Enslaved album), 2004
• Isa (Zaz album), 2021
• Isa (film), a 2014 television film
• Isa, a dance in music of the Canary Islands

• Industry Standard Architecture, a PC computer bus standard
• Instruction set architecture, the specification for data types, registers, instructions, etc. for a given computer hardware architecture
• Is-a, a relationship between abstractions in programming
• Internet Security and Acceleration, a network router, firewall, antivirus program, VPN server and web cache from Microsoft Corporation

• Indian Squash Academy, Chennai, India
• Independent Schools Association (Australia), mainly for sports
• Independent Schools Association (UK), organisation for independent schools in the United Kingdom
• Iniciativa de Salud de las Americas, Spanish name for Health Initiative of the Americas
• Institute for the Study of the Americas, University of London, England
• Instituto Superior de Agronomia, an agronomy faculty in Lisbon, Portugal
• Instituto Superior de Arte, an art school in Havana, Cuba
• International School Amsterdam, the Netherlands
• International School Augsburg
• International School of Aleppo, Syria
• International School of Athens, Greece
• International School of the Americas, San Antonio, Texas
• International Studies Association
• Islamic Saudi Academy

• Income share agreement, a borrowing agreement sometimes used for tuition loans in the United States
• Individual savings account, class of retail investment arrangement available in the United Kingdom
• International Standards on Auditing, professional standards for the auditing of financial information.
• Israel Securities Authority, Israel's national securities regulator

• Interconexion Electrica, a Colombian company operating energy transmission lines

• Independent Safeguarding Authority, former UK child protection agency
• Intelligence Services Act 1994, UK
• Intelligence Support Activity, of the US Army
• Internal Security Agency, secret service and counter-espionage agency in Poland
• International Seabed Authority, for mineral-related activities
• International Searching Authority, for patents
• International Solar Alliance
• Interoperability Solutions for European Public Administrations, EU
• Invention Secrecy Act of the United States Congress
• Iranian Space Agency
• Israel Security Agency or Shin Bet, Israel
• Israel Space Agency
• Israel State Archives, the national archive of Israel
• Italian Space Agency

• Industry Super Australia, the peak body for industry superannuation funds in Australia
• Innovative Software Applications, a company taken over by Sorcim in 1982
• International Federation of the National Standardizing Associations
• International Seabed Authority
• International Socialist Alternative, an international association of Trotskyist political parties.
• International Society of Arboriculture, a non-profit botanical organization
• International Society of Automation, a non-profit professional organization for engineers, technicians, and students
• International Sociological Association
• International Soling Association
• International Surfing Association, the world governing authority for the sport of surfing
• Irish Sailing Association, the governing body for sailing in Ireland
• International Slackline Association

• Isosaccharinic acid, a six-carbon sugar acid
• Intrinsic sympatheticomimetic activity, a term used with beta blockers that are partial agonists
• Infectious salmon anemia, a viral disease of salmon
• International Standard Atmosphere, an atmospheric model of the Earth
• International Seismological Association, former name of the International Association of Seismology and Physics of the Earth's Interior (IASPEI)

• Isa (moth), a genera of moths.

• Intelligent speed adaptation, systems to automatically enforce vehicle speed limits
• International Symbol of Access, blue and white wheelchair symbol
• ISA Brown, type of chicken
• Ideological state apparatus, a theory by Louis Althusser

• Internal Security Act (disambiguation)
• Isaz, the "I" rune in the Scandinavian runic alphabet
• Issa (disambiguation)
• Isha (disambiguation)
• ESA (disambiguation)
• All pages with titles beginning with ISA
• All pages with titles beginning with Isa
• All pages with titles containing isa
• lSA (disambiguation)