McAfee entered Vassar with the Class of 1920 (overlapping by one year with Edna St. Vincent Millay), studying economics, sociology, and English - and playing on her class’s hockey and basketball teams and being active with Vassar's debate team and student government.
She served as the president of her class and president of the Christian Association. Graduating Phi Beta Kappa, she taught elementary and middle-school-aged girls in her home state for three years. In fall 1923, she left Illinois to become an acting professor of economics and sociology at Tusculum College in Greenville, Tenn.
Studying at the University of Chicago during the summers, McAfee earned her M.A. in Sociology in 1928. In 1926 she became Dean of Women at Centre College and stayed there till 1932, when she returned to Vassar as the Executive Secretary of the Associate Alumnae of Vassar College, helping to raise money to build Kenyon Hall. Two years later, McAfee accepted the position of Dean of College Women at Oberlin College.
In 1936, Wellesley College ended an 18-month search involving more than 100 candidates, naming Mildred McAfee its President at 36. Her presidency emphasized truth as the greatest and most precious object of scholarly pursuit, and defended a liberal arts education against accusations of indulgence during the Depression. She told Wellesley students:
I envisage the function of this college, or any college, to prepare an oncoming generation of students to disseminate truth. It is my conviction that truth is more easily given a hearing if it is presented by a healthy, well-adjusted, effective human being who sees the truth in the light of a world-philosophy which gives it meaning.Her presidency of Wellesley was interrupted by World War II. As the United States mobilized against Nazi aggression, the need for women in the Navy became increasingly apparent. The last of the Yeomen (F) left active U.S. Navy duty 23 years before. Only a small number of Navy Nurses represented their gender in the U.S. Navy and they did not have formal officer status. Now, the Navy was preparing to accept a large number of enlisted women and in addition female officers to supervise them.
For this purpose, the WAVES (Women Accepted for Volunteer Emergency Service) was created. Establishing the WAVES was complex because inter-war changes in the Naval Reserve legislation limited service to men. Though some had long known that uniformed women would be a wartime necessity, opinion was against it until Europe was overrun by the Nazis. Even then, it required creativity to get an authorization through The Congress. FDR signed it into law on 30 July 1942.
The next few months saw the commissioning of Mildred McAfee to head the WAVES. she had to manage recruiting, training, administration and uniform design - the basic WAVES uniform design is still in use in the 21st century. Within a year 27,000 women wore it.
These women served in a far wider range of occupations than had the Yeomen (F). Secretarial and clerical jobs still took a large portion of the women but thousands of WAVES also performed new duties in the aviation community, Judge Advocate General Corps, medical professions, communications, intelligence, science and technology.
The wartime Navy's demand for them was intense as it struggled to defeat Hitler and Mussolini in Europe and then the Japanese in the Pacific. At the end of World War II, there were more than 8,000 female officers and 80,000 enlisted WAVES, about 2½ percent of the Navy's total strength. In some locations WAVES constituted a majority of uniformed Naval personnel. Many remained in uniform to help get the Navy into, and through, the post-war era. (A total of 16 million Americans were on active duty in World War II. Of them, 8,000 are still living.)
To take on the job of running the WAVES in August 1942, McAfee took what turned out to be a two-and-a-half-year leave of absence from the Wellesley College presidency. She served at the rank of Lieutenant-Commander, the first woman ever commissioned as an officer in the U.S. Navy. She remained with the WAVES until 1945, was promoted to the rank of Captain, and received the Distinguished Service Medal for her work.
Upon her return to Wellesley, she married Rev. Dr. Douglass Horton, former dean of the Harvard Divinity School and a Congregational Minister. She retired from Wellesley in 1948. After retirement, McAfee worked with her husband in church and civic work and was also an active leader in education and social reform. Having written her M.A. thesis on the YWCA, she worked with the Congregational Church to bridge gaps and create understanding through religion.
She served as a UNESCO delegate, was a director of the New York Life Insurance Company, the NBC, RCA, and the Ford Foundation's Fund for the Advancement of Education. Later she co-chaired the National Women’s Conference on Civil Rights.
McAfee’s husband died in the couple’s New Hampshire home in 1968. She survived him by 26 years, continuing her social and religious work until her own death in 1994. When she died, she had been awarded more than 31 honorary degrees.