Government agencies •
U.S. Office of Palestinian Affairs, a United States government office in Jerusalem managing Palestinian relations •
Office of the Pardon Attorney, an agency of the United States Department of Justice •
Office of Population Affairs, a United States agency providing advice on population issues •
Office of Price Administration, a United States government office set up to stabilize prices and coordinate rationing after the outbreak of World War II •
Oil and Pipelines Agency, a United Kingdom agency •
Ontario Power Authority, a government agency in Canada
Other organizations •
FC OPA, an association football club from Oulu, Finland • Postnominal letters used by the
Anglican Order of Preachers (
Ordo Praedicatorum Anglicanus) •
Online Privacy Alliance, a coalition of Internet companies •
OPA Co., Ltd. (Oriental Park Avenue), a Japanese clothing retail chain and subsidiary of Daiei •
Ordre des Palmes Academiques, an Order of Chivalry of France for academics and cultural and educational figures •
Oregon Pioneer Association, a fraternal-lineage society first established as the Oregon Pioneer Society in 1867 •
Oregon Potters Association, a not-for-profit group of clay artists •
Omega Phi Alpha, a service sorority ==People==