The Peace Research Institute Oslo (; PRIO) is an independent peace and conflict studies research institution, based in Oslo, Norway. It is regarded as the world's "oldest and most prominent peace research center." It was founded in 1959 by a group of Norwegian researchers led by Johan Galtung, the principal founder of peace studies, who was the institute's first director.

The Peace Research Institute Oslo (; PRIO) is an independent peace and conflict studies research institution, based in Oslo, Norway. It is regarded as the world's "oldest and most prominent peace research center." It was founded in 1959 by a group of Norwegian researchers led by Johan Galtung, the principal founder of peace studies, who was the institute's first director.