Catholic education was of great importance to the Gallatin Valley community from the early days.  In 1880, Miss Annie McLaughlin, at her own expense, built a one-room frame building and opened St. Agnes Academy.  She taught school at St. Agnes for seven years, after which time the school closed.  A Professor Rowdy took up Miss McLaughlin's work by opening a Catholic school in the Farmer's Hotel.  The Farmer's Hotel burned down two years later, and the school was closed.  Today, the Bozeman Public Library exists where the Farmer's Hotel used to be.

    In 1915, Bozeman finally got a permanent Catholic school.  The school was a three story brick building built with funds bequeathed to Holy Rosary  by John Cahill.  Mr. Cahill left Holy Rosary his 200-acre ranch in his will, which Father Leitham sold for $15,000.  Father Leitham also purchased a five-room frame house adjacent to the school to serve as a sisters' residence.  Despite his best efforts, Fr. Leitham was unable to find sisters to teach at the school, so the building was rented out to the Public School System.  In 1919 three sisters came from the Franciscan Sisters of Perpetual Adoration, LaCrosse, Wisconsin.  The school was finally open for Catholic education.  The three sisters were Sisters Marcella, Constance, and Athanasia; they taught all eight grades.  In 1920, the first year of high school began and in each of the next three successive years and additional grade was added so that the first high school class graduated in May 1924.

    In September, 1927, Father Leitham was replaced by Rev. John J. O'Kennedy.  By this time, there were nine sisters teaching at the school, so a new residence was desperately needed.  A convent was built in 1928.  Today the convent is now used for small bible study meetings and for our elementary religious education classes.

    In 1938, a gymnasium, three classrooms, an office, and a library were added to the school structure.  Almost all of this addition was built with the help of donated labor.

    In the late 1950s, the old school building needed to be upgraded, especially the high school.  After much deliberation the Parish decided to build a new school.  In 1958 land was purchased on South Fifteenth Avenue and West Koch Street.  The new building was completed in 1962.  The old school was used as a Religious Education Center.

    The 1970s brought higher costs of maintaining the school.  Along with the increased maintenance costs, the economy required increased salaries for the entire staff.  Because of the financial difficulties, the school closed in 1976. 

    In the early 1980s, the Rosary High School Building and some land was sold to the Gallatin County for the Law and Justice Center.  The money from the sale of the school and land was enough to retire the church debt and leave money for upgrading the remaining facilities.