Brother Denis has a B.A. in social sciences and a M.A. in education from St. Mary's University. He also was awarded a Masters in Social Work from the University of Illinois at Chicago and a Masters in religious education from Loyola University in Chicago.
Having served as a high school teacher and administrator, Brother Denis has also been a campus minister at Lewis University and Bethlehem University in Palestine. He has taught courses in theology at St. Mary's University and Lewis University. A co-founder of Su Casa Catholic Worker, Brother Denis served as a co-director of the house of hospitality and served on staff until he relocated to coordinate services at Bethany Catholic Worker in Winona, MN.