Based on the manner in which Arnoldus Gheyloven refers to himself in his works, that is, Arnoldus Theoderici de Hollandia de Rotterdam, one may believe that Arnoldus was born in the city of Rotterdam, probably around 1375, but the exact date of birth remains unknown. Hardly anything is known about his younger years or the social environment in which he spent his childhood. After having studied in Vienna for a while, Gheyloven moved to Bologna around 1393 in order to study canon law under the supervision of Gaspar Calderini (†1399), a subtilis canonista according to Gheyloven, and son of the even more famous canonist, Giovanni Calderini (†1365). Arnoldus stayed for six years in the house of Calderini, where he was nourished by him as if he was his own son. But when Calderini died from the plague in 1399, Gheyloven moved to Padua, as a baccalaureus decretum, to continue his canon law studies, between 1401 and 1403, under the supervision and sponsorship of the great Italian canonist, Francesco Zabarella (†1417).