ARPA
- .arpa
- ARPA-E
- ARPA-H
- ARPA-I
- Advanced Research Projects Agency
- Aerolíneas Paraguayas
- Agenzie Regionali per la Protezione Ambientale
- Akhurian River
- Amazon Region Protected Areas Program
- American Rescue Plan Act of 2021
- Archaeological Resources Protection Act of 1979
- Areni
- Arpa (river)
- Arpa (river), Chhattisgarh
- Arpa Chai (disambiguation)
- Arpa Darreh
- Arpa Ke'un
- Arpa Valley
- Arpa Yeghegnadzor
- Arpa d'Eolo
- Arpa jarocha
- Arpa şehriye
- Arpi, Armenia
- Automatic radar plotting aid
- Average revenue per account
- Biomedical Advanced Research and Development Authority
- DARPA
- HSARPA
- IARPA
- José Arpa
- National Institutes of Health
- Office of the Director of National Intelligence
- Okay Arpa
- Rinaldo dall'Arpa
- US Department of Energy
- US Department of Homeland Security
- US Department of Transportation
- Yvan Arpa