RSA may refer to:

• Rabbinical Seminary of America, a yeshiva in New York City
• Regional Science Association International (formerly the Regional Science Association), a US-based learned society
• Renaissance Society of America, a scholarly organization based in New York City
• Rhetoric Society of America, an academic organization for the study of rhetoric
• Royal Scottish Academy, a Scottish institute of the Arts
• Royal Society of Arts, a British charitable organisation, formally the Royal Society for the Encouragement of Arts, Manufactures and Commerce

• Redstone Arsenal, a United States Army post adjacent to Huntsville, Alabama
• Royal New Zealand Returned and Services' Association, an organization for the welfare of veterans of New Zealand's military
• Royal School of Artillery, a British Army training establishment for artillery warfare
• Royal Signals Association, an organization for serving and retired members of the Royal Corps of Signals, of the British Army

• RSA Insurance Group (Royal and Sun Alliance), United Kingdom
• RSA Security, a US network security company
• Rehabilitation Services Administration, a US Department of Education agency
• Retirement Systems of Alabama, US
• Ridley Scott Associates, a UK film company
• Road Safety Authority, Ireland
• Russian Ski Association

• Republic of South Africa, IOC country code
• Santa Rosa Airport (Argentina), in La Pampa province (IATA code RSA)

• Respiratory sinus arrhythmia, the heart rate variation due to respiration
• Retrosynthetic analysis, in organic chemistry
• Rsa RNA, partially characterised non-coding RNA from Staphylococcus aureus
• Root System Architecture

• RSA (cryptosystem) (Rivest–Shamir–Adleman), for public-key encryption
  • RSA Conference, annual gathering
  • RSA Factoring Challenge, for factoring a set of semi-prime numbers
  • RSA numbers, with two prime numbers as factors

• RSA (missile), a Swiss-developed surface-to-air missile system
• Rational Software Architect, part of IBM Rational Application Developer
• Remote supervisor adapter, an out-of-band management interface on IBM servers
• Revolver Stechkina-Avraamova, a designation of the Russian OTs-01 Kobalt revolver
• Roentgen stereophotogrammetric analysis, also called radiostereometric analysis, a method of calculating 3D orientation using X-ray images

• Ray Steadman-Allen, a composer of music
• Repressive state apparatuses, a concept in Louis Althusser's philosophy
• Responsible Service of Alcohol, alcohol server training in several Australian states
• Revenu de solidarité active, French benefit for low-paid workers
• New Hampshire Revised Statutes Annotated, an entire body of laws
• Runway safety area, or runway end safety area, for aircraft