Remembering Sister Joan Gannon, OSB

Updated: Aug 3



Our dear Sister Joan died on May 6, 2020, after a long illness, the last child of her family. She was preceded in death by her parents, George and Hannah, her sisters Margaret Mary Flau, Sister Mary Ann Ida, BVM, Aileen Gannon, and Elizabeth Harrell and her brother, Judge John Gannon. Funeral arrangements are pending. She passed into the loving arms of God and the Sisters who have gone before her are there to welcome her. Born in Chicago, she and her family were active members of St. Jerome's Parish in Rogers Park. After attending St. Scholastica High School, in June 1940, she wrote a letter to the Prioress of the Benedictine Sisters of Chicago to express interest in joining the community. On September 7, 1940, she was accepted as a postulant. On July 11, 1941, she became a novice and on August 16, 1942, she professed triennial vows. Sister Joan will be remembered for being a truly genuine person. She was forthright and spoke her mind. Her life had held both happiness and hardship. She had a cheerful spirit and a ready smile. She appreciated and enjoyed friendly conversations. Whether using one of her several degrees or giving of her time to serve in whatever way, Sister Joan was a loyal community member, serving where there was need. We invite you to learn more about Sister Joan in the following biography written by Sister Benita Coffey, OSB.

1940 St. Scholastica High School senior yearbook photo of Sister Joan Gannon, OSB.


Mary Joan Gannon, the youngest of six children, was born on March 6, 1923 to George Thomas and Hannah Murphy Gannon. She was baptized on March 25. She grew up in Rogers Park, a neighborhood of Chicago, with her four sisters and her only brother. Together their family were active members of St. Jerome’s Parish where they attended school. Mary Joan was confirmed in May of 1933.


For secondary school, Mary Joan went to St. Scholastica High School, not far from home. Later in life, she spoke of feeling the Sisters there had a gift of kindness and openness to all. Though in her mind she considered herself one of the “lower lights of the school population”, the school yearbook said that she was “Brimful of ingenious ideas – imbibes more than her quota of laughs and fun.”


Sister Joan Gannon, OSB in full habit.

When Sister Joan in later years told her vocation story, she mentioned the happiness she experienced on the night of the Senior Play, As You Like It, when her call to religious life “crystalized into words for her.” In June, 1940, she graduated and she wrote a letter to the Prioress to express her interest in joining the community, and only afterward told her parents. Before that, none of the Sisters had known about her desire to join them.


On September 7, 1940, Mary Joan was accepted as a postulant. On July 11, 1941, she became a novice and thereafter she would be known as Sister Denise. On August 16, 1942, she professed triennial vows. The next month she began her first teaching assignment to teach first grade at St. Hilary Parish, where she was also to serve as one of the sacristans. Her natural gift with small children became evident and soon she was teaching kindergarten.


Sister Denise professed her perpetual vows on August 16, 1945 and continued to serve at St. Hilary until 1948 when she was assigned to Mother of God, in Waukegan, Illinois. Then in 1951, she was asked to teach kindergarten at Queen of All Saints, in Chicago.


Sister Joan Gannon, OSB showing the typewriter to those present.

Her teaching was interrupted when she lost her voice and spent a year at the monastery serving in several quiet and caring ways by working in the altar bread department and helping in the infirmary with the retired Sisters.


In fall of 1953, she resumed teaching again, this time on the high school level at St. Scholastica Academy in Cañon City, Colorado, a boarding school. There she taught English and math, helped with laundry and sacristy, and managed the student Snack Bar.


It is to be noted that during all these years, she was also working to complete her undergraduate degree, a Bachelor of Science in Math at DePaul University, in Chicago.


Sister Joan Gannon, OSB enjoying a magazine.

When she completed this degree, it was clearly not to be the end of her formal studies. She attended the National College of Education for kindergarten studies; and she took courses at Mundelein College, where she later earned her Masters in Religious Studies. Her ingenuity and well-written applications to the National Science Foundation saw her awarded grants to attend Xavier University in Cincinnati, the Illinois Institute of Technology for Computer Programming, North-eastern Illinois University for Nuclear Chemistry, and the University of Illinois in Champaign for Chemistry.

A faculty photo of Sister Joan Gannon, OSB, formerly Sister Denise.

Sister Denise joined the faculty of St. Scholastica High School in 1956, where she began teaching Chemistry and Math. She managed the Candy Store and was Moderator for a Young Christian Student group for two years. In June 1967 she discontinued teaching for three years and served in the monastery infirmary. In fall 1970 she assumed responsibility for the school’s Language Lab and also worked in the Business Office. During the nine years of this ministry, she also actively participated with the School Board of SSA. It was during this time of Vatican II and renewal that she opted to resume using her baptismal name, as did many Sisters.


Sister Joan Gannon, OSB (left) with Sister Johnette Sawyer, OSB (right) exiting St. Scholastica Chapel after liturgy.

In fall 1979 Sister Joan went to Canada to study Pastoral Ministry at St. Paul University in Ottawa. With this training, she served at several Chicago parishes, including Our Lady of Lourdes and St. Thomas Aquinas on the westside. Finally she returned to St. Jerome’s in Rogers Park, her home parish. Here, she was devoted to visiting the homebound and also coordinating activities for senior citizens groups. Sister Joan’s happy disposition added joy to the Tip Toppers, and their gratitude in turn energized her.


After 1989, her work varied and was mainly within the monastery. This included serving at the switchboard and in the sacristy, care of the aviary in the infirmary, and caring for plants, and keeping candy dishes full. For fourteen years, she continued to take great pleasure in meeting with the Tip Toppers at St. Jerome’s, even after she had moved into St. Joseph Court Infirmary.


Sister Joan Gannon, OSB with an original art piece (left) and dressed in a fun hat (right) for the St. Joseph Court Infirmary annual tea party.

Sister Joan will be remembered for being a truly genuine person. She was forthright and spoke her mind. Her life had held both happiness and hardship. She had a cheerful spirit and ready smile. She appreciated and enjoyed friendly conversations. Whether using one of her several degrees or giving of her time to serve in whatever way, Sister Joan was a loyal community member, serving where there was need.


Sister Joan Gannon, OSB (right) pictured with some of her community members.

Sister Joan died on May 6, 2020 after a long illness, the last child of her family. She was preceded in death by her parents, George and Hannah, her sisters Margaret Mary Flau, Sister Mary Ann Ida, BVM, Aileen Gannon, and Elizabeth Harrell and her brother, Judge John Gannon. Funeral arrangements are pending. She will be buried in All Saints Cemetery in Des Plaines, Illinois. She is mourned by her Benedictine Sisters, those with whom she ministered, and by her extended family.

To read the reflection given at her memorial (TBD) by Sister Judith Murphy, Prioress, click here.

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