[1] He studied literature and philosophy, however he became increasingly politically active.
Grepp was elected after university studies in the Labor Party's central board in 1912.
As an organizer and tactician, Grepp was probably one of the foremost in the Norwegian labor movement.
In his last years, Grepp was plagued by illness, and he gave his last public speech in 1920.
A street is named after Grepp in the Sagene borough of Oslo.