The Wilderness School was established in 1884 by Miss Margaret Hamilton Brown. Her youngest sister, Mamie, then aged five, was considered too delicate to walk to the local State school and so it was decided that Mamie should be educated at home by Margaret, a trained teacher.

The school opened in their home on Mann Terrace, North Adelaide, with three girls and a boy as pupils. In 1885 the school moved to a site on Northcote Terrace, north of its present site, and in 1893, having outgrown that building, moved again to its present location at 30 Northcote Terrace, Medindie. Both boys and girls attended, although boys left when they turned eight or nine and were old enough to attend boys' private schools. Originally only kindergarten and primary classes were offered, but as the students progressed through the school, the higher levels were offered.

By 1895 there were sixty-two students on the roll, and eighty-three by 1900. It is thought that the first boarder arrived in 1893 and by 1906 there were as many boarders as could be accommodated. As the school grew, so the younger Brown sisters became involved. Miss Margaret was headmistress, Miss Wynnie was in charge of the Kindergarten, Miss Annie took on the role of housekeeper and the care of the boarders, and Miss Mamie, the first pupil, joined the teaching staff in 1898. The school thus became known as "The Misses Brown's School", although its correct name was The Medindie School and Kindergarten. In 1918 the name became "The Wilderness", partly because of the wilderness-like nature of the grounds and partly because the idea of "Forty years in the Wilderness" had such a permanent ring about it.

Margaret Brown believed in higher education and self-reliance for girls, aiming to equip them for full participation in public life, as well as for the role of wife and mother. She strove to provide a sound academic education, although the expectations of her clientele also required training in feminine accomplishments and behaviour. During the First World War the school acquired its badge, a gold lion rampant and the motto "Semper Verus" (Always True). With the badge came the first stages of a school uniform, a brown blazer for tennis team members, with the school badge on the pocket, and by 1926 uniform was being worn throughout the school.

By the late thirties Wilderness was flourishing, having survived the effects of the Depression and taken on many new girls from other private schools which closed as a result of those difficult years.

World War 2 brought some changes to the normal school routines, with black-out arrangements for the boarders, trenches in the gardens, air-raid drill and the arrival of English girls sent out to relatives in Adelaide. With the end of the war and the return of so many former scholars, the Old Scholars Association held a belated Diamond Jubilee in 1946, celebrating the achievements of the Brown sisters, including the publication of "The Wilderness Book", the first history of the school.As the Misses Brown grew ol

der they became increasingly concerned about the future of the school after their deaths, and in 1948 they transferred ownership of the school to a Company and Council of Governors. Miss Mamie, who had gradually taken over as Headmistress from Miss Margaret, retained her position as Headmistress until her retirement in 1951. 1949 saw the culmination of the Browns' services to education in South Australia, when Miss Margaret was awarded the OBE. She died in 1952, sixty-nine years after establishing her school. Miss Mamie Brown, foundation scholar, headmistress and the last surviving Brown sister, died at the end of 1969.

The School has continued to thrive under the guiding hand of the Council of Governors. Although the running of a school today bears little resemblance to the administration of a small private school at the turn of the century, the Brown traditions have been kept alive in a happy and caring family atmosphere, combined with academic excellence of which they would have been proud.