 Cullen was sent by Archbishop Krol to study social work at the University of Pennsylvania, later earning his Master of Social Work degree in 1970.This was followed by a Master of Religious Education from La Salle University (1971) and Master of Divinity from St. Charles Borromeo Seminary (1974).From 1979 to 1993, he served as a chaplain at St. Edmond's Home for Children in Bryn Mawr.