She received the religious habit on Aug. 29, 1937 and her religious profession on Sept. 1, 1940. Sister Mary was awarded a bachelor's degree and a master's degree in general professional education from Seton Hall University, South Orange, N.J.

She taught and served as principal at schools New Jersey, Pennsylvania and Rhode Island. She spent her last decade in the classroom, 1991-2001, teaching Junior High at Villa Walsh Academy in Morristown. Known as an excellent teacher and dedicated principal, Sister Mary not only formed children, but also mentored teachers, colleagues said. When Sister Mary retired from teaching she assisted in the Finance Office and as telephone operator at Villa Walsh. In 2010 Sshe became a resident of St. Joseph Hall, Villa Walsh, Morristown, NJ.

Sister Mary is survived by her sister, Gina Czyechowicz, brother John De Angelis and nieces and nephews. She is predeceased by her parents John De Angelis and Nazzarena (Carminucci), and her sisters Ann Testani, and Amelia Ford; and brothers James, George and Frank De Angelis. A Mass of Christian Burial was celebrated Sept. 2, in Morristown by Father John Rossi, director of Cathlic identity at Paul VI High School, Haddon Township. Interment took place at Ave Maria Cemetery. Donations in memory of Sister Mary De Angelis will be accepted to St. Joseph Hall, c/o Sister Ascenza Tizzano, MPF, Provincial Superior, Villa Walsh, 455 Western Ave, Morristown, NJ 07960-4928.