St. Mary's College at Dallas, a college for women, was founded by Alexander C. Garrett, bishop of the Protestant Episcopal Church in the Diocese of Dallas. Construction began in 1886 on a site on Ross Avenue, but there were interruptions caused by lack of funds, and the building was not completed until the spring of 1889. On September 10, 1889, the college opened with seventy-six pupils, of whom forty-seven were boarders. In 1900 Hartshorne Memorial Hall was completed. The hall had recitation rooms and a chapel on the first floor; on the second floor were bedrooms and bathrooms "with porcelain lined iron bathtubs." By 1903 there were twenty-seven teachers. The curriculum provided for B.A. and B.S. degrees, and under certain circumstances the M.A. was also awarded. A separate chapel was completed and consecrated on May 10, 1908, as a gift of the Belo family in memory of Alfred H. Belo of Dallas.
St. Mary's College was particularly close to Bishop Garrett's heart. He often lectured on astronomy, psychology, and logic. He lived near the college and was always interested in the life and problems of the students. The faculty generally was well qualified and included many who were born and educated in Europe. In spite of good work and high scholastic standing the college had constant financial difficulties. In 1914 the Diocese of Dallas appealed for a special offering for St. Mary's as an act of thanksgiving for the fortieth anniversary of Bishop Garrett's consecration. There was a fairly satisfactory response to this campaign, and the college was reorganized on a better basis. Garrett Hall was completed and dedicated in 1917, but the financial problem had not been solved. By the early 1920s St. Mary's became a junior college, and it was accredited by the State Board of Education. In April 1927 St. Mary's property was transferred to St. Matthew's Cathedral Parish which assumed all liabilities, but St. Mary's College was obliged to close in June 1930. Among the college's students were Margaret Bell Houston, Clyde Giltner Chandler, and Claudia Taylor, who later married Lyndon B. Johnson.