Reitz Memorial took the place of two other high schools: Bosy’ Catholic  High and Assumption Academy, a girls’ school. It was financed by Francis Joseph Reitz. The building was decided on Jan. 1, 1925, by Indianapolis Bishop Chartrand. In the early years, boys and girls were taught on separate floors and by separate faculties. Holy Cross Brothers taught the boys and Sisters of Providence taught the girls. In later years, some Benedictines and Franciscans, as well as lay teachers, joined the faculty. A new wing was added in 1969, and another dedicated in January 2000. At that time, the older sections of the building were renovated.

At first, the sisters continued to reside at the Assumption Convent. In 1938, Rev. Pierre Brisse, the new Assumption pastor, asked that his grammar school have its own principal, instead of the Reitz Memorial one. For this reason, the sisters teaching in the high school needed their own convent. A house was purchased, paid for by donations from several parishes. Five of the sisters moved in to the convent in February 1939. After additions were made to the house, all the sisters were established there by Nov. 8, 1939. In February 1968, ground was broken for a new convent. The sisters moved in during Holy Week in 1969. By 1979, only a few of the sisters at the convent were teaching at Reitz Memorial, and in February 1988, Rev. Ray Kuper, the superintendent of schools, informed the sisters that, because there were fewer than seven sisters living there, they would have to vacate the convent by the first of September. All the sisters left by Aug. 15. The last Sister of Providence to teach at Reitz Memorial left in 1994.