 Virginia Perrin Speed (1879–1968) and her husband William Shallcross Speed (1873–1955) were the principal founders and sustainers of the school, and are largely responsible for the school's success

Needing more land to grow, Collegiate moved in 1927 to its current home on Glenmary Avenue in the historic Highlands, just east of downtown Louisville, in what is now the Lower School.Although the school initially accepted boys in the primary grades, it remained traditionally a girls' school until 1972 when the Lower School became coeducational.In 1980, Collegiate's Board of Trustees established coeducation in the Upper School.