Harpviken is foremost known for his competence on Afghanistan, where he has travelled extensively and conducted multiple field works since he first engaged with the country in 1989.

Between studies, Harpviken has served as agricultural coordinator and director for the Norwegian Afghanistan Committee in Peshawar, Pakistan (1990–92).

[1] Harpviken has participated and led multiple long-term research projects on anti-personnel landmines, internally displaced and refugees, peacebuilding, as well as regional security.

Harpviken's expertise and research interests include the dynamics of civil war (mobilization, conflict resolution, post-war reconstruction and peacebuilding), migration and transnational communities, and methodology in difficult contexts.

As director of PRIO, he speculated and commented each year on the Nobel Peace Prize in media outlets from all over the world.