Caroline Dondanville the eldest daughter and second of nine children, of Wallace Dondanville and Elizabeth Sherman was born in Serena Township, La Salle County, Illinois on May 13, 1872. Affectionately known as Carrie she received her early education in Serena Township schools and attended high school at St. Xavier Academy in Ottawa, Illinois. She entered the convent of the Sisters of Mercy in Ottawa as a postulate in 1893. On February 13, 1896 she professed her final vows taking the name Sister Mary Isabel.
As a young girl she exhibited a natural talent for arts, winning prizes at the La Salle County Fair. Her interest was encouraged by famed sculptor and teacher Lorado Taft who came to Ottawa to lecture and to use the natural clay found there in his modeling. Isabel was a frequent visitor to his studio in Chicago. In 1912-13 she traveled extensively in Europe perfecting her artistic techniques. She was finishing a year's study in Munich when World War I broke out.
Between 1896 and 1929 Sister Isabel served at St. Xavier Academy in Ottawa in many capacities. She was art teacher, Mistress of Novices for nine years and eventually Superior. When her brother Edward became Pastor of St. Thomas Aquinas Church in Chicago in 1925 she was called upon to design the stained glass windows for the church.
In 1929 Isabel returned briefly to Europe to further her study of art. Upon return she transferred to the Chicago province of the Sisters of Mercy which had amalgamated with the Ottawa order. She became a member of the Provencal Council of the Sisters of Mercy and took up residence at St. Xavier College at 4900 South Wabash. She taught art at St. Xavier until her retirement in 1950. In her retirement she gave private art lessons and served as "post mistress" for the nuns of St. Xavier. In 1956 she celebrated the 60th anniversary of her religious profession.
The halls of St. Xavier Academy in Ottawa and the College in Chicago proudly wore the marks of Sister Isabel's hand. Her deft brush painted hundreds of pictures of flowers and outdoor scenes that kept the two schools interiors bright. She was particularly adept at copying madonnas and works of 19th Century European artists. She exhibited her work widely, often in competition.
In 1957 St. Xavier College moved to a new location at 103rd Street and Central Park. Sister Isabel was transferred to a Sisters of Mercy nursing home on Belmont Avenue. She served as "post mistress" for the facility and continued to work with her art. She celebrated her 90th birthday on May 13, 1962 in Deerfield, Illinois at the homes of her nephews Laurence and Louis. Isabel died at the nursing home on Belmont Avenue in Chicago on June 1, 1965. She was buried at Columbia Cemetery in Ottawa, Illinois.