William Greenleaf Eliot, a prominent Unitarian minister in St. Louis and educational pioneer who co-founded Washington University in St. Louis in 1853, took another bold step establishing a school for girls in 1859: Mary Institute was named for his daughter, Mary Rhodes Eliot, who had died at age 17.
From the start, the School prospered. In 1928, an alumna donated 22 acres, Washington University added 18 more, and Mary Institute soon had a new campus in the country at Ladue and Warson Roads.
Shortly before Mary Institute's founding, Washington University established an "academic sub-department" for boys. In 1879, it was named "Smith Academy" and began operating in downtown St. Louis with an enrollment that eventually grew to 385. By the second decade of the 1900s, Smith's fortunes had declined due to growing competition and the diminished importance of the school's intended role as a feeder for Washington University. Recognizing Smith's situation, a group of local community leaders met to discuss the "country day school" movement, then taking shape nationally, of relocating schools away from congested cities to foster high academic standards and discipline in a healthier rural setting. These discussions led to the opening of St. Louis Country Day School in 1917, a few months after Smith Academy closed its doors. Country Day, teaching grades 5-12, occupied a 55-acre campus in north St. Louis County, near the municipal airport, until late 1957, when airport expansion prompted relocation to a large parcel of land adjacent to Mary Institute.
Program coordination between the two schools evolved over the years, and in 1992, a full-scale merger was approved creating a single school -- Mary Institute and Saint Louis Country Day School (MICDS) -- with one board, administration, faculty, student body, and common curriculum.
Today, MICDS is considered one of the nation's pre-eminent independent schools, and it is continuing to shape a new generation of stellar graduates and world leaders.