Msgr. Dempsey grew up on the northwest side of Chicago where his family were parishioners of Queen of All Saints Parish.  He attended parochial school there and went on to study at Quigley Preparatory Seminary North and Niles College.  He has attended several universities where he received advanced degrees including Loyola University, Chicago; North American College, Rome; Pontifical Gregorian University, Rome; and Pontifical University of the Holy Cross, Rome.   

Msgr. Dempsey was ordained in 1980 and he served as an Associate Pastor at St. Joseph’s, Libertyville (1980-1985); St. Ferdinand’s, Chicago (1985-1990); and St. Wenceslaus, Chicago (1990-1991).  In 1991, he was appointed the editor of the Vatican’s newspaper and was in Rome for ten years.  In 2001, he returned to the Archdiocese and resided at St. Patrick’s, Wadsworth, and St. Peter’s, Skokie while pursuing doctoral studies in theology. He is also very active within the Archdiocese and the Liturgical Institute of the University of St. Mary of the Lake.