The death of his father forced Stjerna to find employment at the newspaper Sydsvenskan to support his family, while continuing his studies at the university.

He switched however to studying archaeology, in part because of the resistance he was met with for his "hypercritical" method of analysing legendary stories.

In 1905, he obtained his Ph.D.[1] Stjerna began teaching at Uppsala University in 1906, sharing responsibilities with Oscar Almgren, and took on a full-time position as lecturer in Scandinavian and Comparative Archaeology in 1907.

[1][2] That same year he undertook a major archaeological excavation in Uppsala with his students, after construction in the city uncovered the remains of medieval buildings.

[5] Stjerna's articles were credited with "providing a most welcome addition to the critical apparatus of the poem", by supplementing the meagre historical record with observations gleaned from archaeological research.