[1] In the winter and spring of 1904–05, he participated in a study group to Rome, Sicily and North Africa.
Later on, he furthered his education at the Campo Santo Teutonico in Rome (1908–11), followed by an appointment as associate professor of religious history at Westphalian Wilhelms-University in Münster (1911).
[1][2] Dölger's primary focus involved investigations of the early Christian church and its relationship with non-Christian societies.
[2] He also published scholarly works on the sacrament of confirmation, on exorcism, on baptism, and on the Eucharist in ancient Christianity.
In 1929 he founded the journal Antike und Christentum ("Antiquity and Christianity"), of which he contributed a series of detailed studies of the early church.