Research interests include Old Norse Philology, Language History, Landscape History, Archaeology and Viking Studies, and Medieval History. Stefan has produced over 180 academic books and articles and is the Editor of Acta Scandinavica. In 1997 he became a Fellow of The Royal Gustavus Adolphus Academy and a Fellow of The Royal Swedish Academy of Letters, History and Antiquities in 2008.  Research interests include;
Society, Culture and Languages of Early Scandinavia
The Christianization and Early Church Organization in Scandinavia
Landscape Studies (Scandinavia)
Language and History in the Early Germanic World
Viking Slavery
Germanic Place-Names
Early Law in Scandinavia
Old Norse Mythology

Honorary Research Associate, Dept. of Anglo-Saxon, Norse and Celtic, University of Cambridge
Formerly The Sixth Century Chair in Scandinavian Studies
Adjunct Professor in Archaeology at the University of Aberdeen
Associate Professor (Docent) in Scandinavian Language at Uppsala University
Fellow of The Royal Society of Edinburgh
Fellow of The Royal Swedish Academy of Letters, History and Antiquities, Stockholm
Fellow of the Royal Gustavus Adolphus Academy, Uppsala
Member of The Institute of Advanced Studies, Princeton 2017-18


Editorship
Editor of the Journal Viking and Medieval Scandinavia (Brepols)
Editor of the Series Studies in Viking and Medieval Scandinavia (Brepols)
General Editor of the Series Acta Scandinavica (Brepols)
General Editor Medieval Nordic Laws (a subseries to Routledge Medieval Translations) (Routledge)
Member of the Editorial Board of Northern Scotland (Edinburgh University Press)