In addition to collecting Norwegian folksongs and traditions and writing on Runic inscriptions, he made considerable contributions to the study of the Celtic, Romance, Oscan, Umbrian and Etruscan languages.

In his 1881 work, Studier over de nordiske Gude- og Heltesagns Oprindelse (Studies on the Origin of the Nordic Legends of Gods and Heroes), Bugge theorized that nearly all myths in Old Norse literature derive from Christian and late classical concepts.

His principal work, a critical edition of the Poetic Edda (Norrœn Fornkvæði), was published at Christiania in 1867.

He maintained that the Eddic poems and the earlier sagas were largely founded on Christian and Latin tradition imported into Scandinavian literature by way of England.

trans., The Home of the Eddic Poems, 1899); Norsk Sagafortælling og Sagaskrivning i Island (Christiania, 1901), and various books on runic inscriptions.

Professor and linguist Magnus Olsen, who was Bugge's assistant and successor, read and described new discoveries of inscriptions.