The city of Flint Hill was founded in 1836 by Captain Taliaferro P Grandham. In 1883 with approximately 20 families in the parish the first Catholic Church was built in Flint Hill. In 1893 a Catholic school with 10 boys and nine girls was started and taught by a lay teacher. Just 5 years later there were 32 children enrolled with classes still taught by the lay teacher. With the parish growing, a new church building (the current church) was built in 1900 and the original church building was converted into a two-room school which housed approximately 60 students.
With enrollment growing the Sisters of the Most Precious Blood from O’Fallon were brought in to teach starting in 1903. By 1913, with approximately 90 students enrolled a new brick school building was completed and the old frame school was torn down. In 1919 the school program was expanded when Fr. Von Brunn required children to attend school for eight years to graduate.
Due to financial conditions, the St. Theodore Catholic School became a public school in 1936, but religious instruction and activities were still permitted. By the late 1940’s political conditions had drastically changed and religious instructions and activities had to be done outside of regular school hours. In 1953 as a result of state court decisions, the St. Theodore Catholic School ceased being a public school and the financial responsibility for the school returned to the parish.
Growth continued with the introduction of school bus transportation in 1954. 12 year later, in 1966 two classrooms were added to the school building and in 1969 enrollment peaked at 167 students. In 1971 Fr. Portucheck was named pastor and in his time the first school board was initiated and Eucharistic liturgies for children were introduced once a week.
Sadly, in 1981 news came that the sisters were leaving the parish, leading to an increased financial burden of operating school. This same a year the first self-study and accreditation was completed. The following year, the school year opened with a full lay faculty with Mrs. Delores Schaeffer as the principal. Just one year after the departure of the Precious Blood Sisters, St. Theodore parish celebrated its centennial in 1983.
In 1994 a long-term planning study was started but never completed or implemented due to the retirement of Fr. Knoll. Major renovations began in 1996 when the loft of the auditorium of the school building was renovated and turned into a library and major works was done to the kitchen and school cafeteria. Likewise, in 1996 a kindergarten program was initiated and a computer lab was opened.
A third self-study was completed in 1997 and in 1999 planning for new buildings and renovation of the older buildings was begun. One year later, with the approval of the Archdiocese construction was begun on renovations and the new building. The new building would include parish/school offices, teacher workroom and lounge, a parish center / gymnasium, cafeteria, 5 new classrooms, increased restroom and additional storage space. The new facility, having been dedicated by Bishop Nauman, opened for the 2001 – 2002 school year
In 2005 school enrollment grew to 179 students and 113 families. In the summer of 2019 the parish offices were moved to a separate building on the campus. In the fall of 2021, the preschool was fully integrated into the St. Theodore School. Starting in the fall of 2022, Mrs. Molly Molitor became the principle. Today St. Theodore is a growing and thriving school of 252 k-8 students and 55 preschool students .