Editing OSI (section)

==Organizations==
* [[Oblates of St. Joseph]], a Roman Catholic Religious order that uses the postnominal initials O.S.I.
* [[Open Source Initiative]], an organization dedicated to promoting open source software
* [[Open Society Institute]], a private charitable foundation established by George Soros to promote open societies around the world
* [[Open Society Institute-Baltimore]], a locally based foundation that is part of Open Society Foundations
* [[Open Space Institute]], an organization that seeks to preserve scenic, natural and historic landscapes
* [[Ordnance Survey International]], a former subsidiary of the UK Ordnance Survey mapping agency
* [[Ordnance Survey Ireland]] (''Suirbhéireacht Ordanáis Éireann'')
* [[Otto-Suhr-Institut]], the political-science institute of the Free University of Berlin

===Companies===
* [[OSI Group]], an American holding company of meat processors that service the retail and food service industries
* [[OSI Pharmaceuticals]], an American pharmaceutical company
* [[OSI Restaurant Partners]], the restaurant and entertainment group that includes Outback Steakhouse
* [[OSI Systems]], a company that manufactures security scanners and medical equipment based in California
* [[OSIsoft]], a privately held company that develops device connectivity software
* [[Objective Systems Integrators]], a company that provides monitoring software for communication networks
* [[Open Systems International]], an automation software vendor for the electric, petroleum, transportation and water industries
* [[Officine Stampaggi Industriali]], a defunct Italian coachbuilder
* [[Ohio Scientific]] Inc. (also known as Ohio Scientific Instruments), a US microcomputer manufacturer 1975-1981

===Government===
* [[Office of Scientific Intelligence]], former name of a department of the Central Intelligence Agency now called the Directorate of Science and Technology
* [[Office of Strategic Influence]], a former American government agency, part of the Department of Defense and focused on psychological warfare
* [[Office of Special Investigations (disambiguation)]], a name shared by several government agencies
** [[U.S. Air Force Office of Special Investigations]]
** [[Office of Special Investigations (Government Accountability Office)]]
** [[Office of Special Investigations (United States Department of Justice)]]
* Office of Scientific Integrity, now [[United States Office of Research Integrity]]
* Office of Special Investigation, a secret intelligence unit of [[Republic of Korea Air Force]]
* Office of the Special Investigator Australia