In 1888, he was named docent of Finnish and comparative literature at University of Helsinki. In 1889, he was named acting professor of Finnish and Finnish literature and in 1898, extraordinary personal professor of Finnish and comparative folklore. In 1898, Krohn became a full professor at the University of Helsinki for
Finnish and
comparative folklore. In 1908, when a permanent chair in Finnish and comparative folklore was established, he became its first occupant. In 1907, he created the Federation of Folklore Fellows' Communications with his friends Johannes Bolte and
Axel Olrik. In 1917, he became chairman of the
Finnish Literature Society (Suomalaisen Kirjallisuuden Seura). In 1918, Krohn published
Kalevalankysymyksiä ('Kalevala Questions'), a two-volume handbook designed for students of Finnish folk poetry. In
Kalevala Questions Krohn completely reworked his position on the historicity of the
Kalevala. Krohn had previously argued that the
Kalevala evolved from small "poetic germ cells" that merged to form a
heroic epic. In
Kalevala Questions he instead took the position that the poems were born as complete works, and had fragmented over time. Krohn argued that the poems were composed at the same time as the Scandinavian
Viking Age, and were accounts of real historical events. This was in stark contrast to his previous view of the
Kalevala as a work of Medieval origin that borrowed significantly from
hagiography. While Krohn attributed his change in opinion to his further analysis of "observed facts," he also admitted the influence of the political climate that had emerged following
Russification and the
Finnish Declaration of Independence. Writing for the nationalist paper
Uusi Suomi in defense of his new position, Krohn stated that "The formerly peaceful nation of Finland has become militaristic [...]
Kalevala scholarship has followed the same road." Eight years later, he reworked the book for a foreign audience, added folktale examples and published it as
Die folkloristische Arbeitsmethode ('Folklore Methodology'), which since that time has served as the standard reference work for the Finnish Method. In 1932, a year before he died, Krohn returned once more to folklore research. He published
Übersicht über einige Resultate der Märchenforschung ('A Review of Some Results of Folktale Research'), a review of international folktale scholarship that was based largely on the methodological approach he had developed. ==Publications==