[citation needed] He attended one of the 'Humanistisches Staatsgymnasium' in Vienna, a grammar school in which the classical languages Latin and ancient Greek are taught as the basis of European culture.
Between 1926 and 1930 he co-edited the new serial "Kritische Berichte zur kunstgeschichtlichen Literatur" (founded by Pächt and Bruno Fürst [Wikidata] and in 1931 and 1933 edited the first (and only) two issues of Kunstwissenschaftliche Forschungen in collaboration with Sedlmayer).
Shortly before the Anschluss, in 1936, Pächt left Austria to accept an invitation by the Irish George Furlong, Director of the National Gallery of Ireland.
From 1969, Pächt headed the Department of Manuscripts at the Austrian National Library, and following his retirement in 1972, he compiled and edited a catalogue of illuminated manuscripts of the Vienna National Library, which appeared 1974 under the title "Die illuminierten Handschriften und Inkunabeln der Österreichischen Nationalbibliothek" as vol.
[citation needed] Photographs by Otto Pacht are held at the Conway Library in the Courtauld, London, and are being digitised.