Sweeney taught physics and chemistry at
Campbell-Hagerman College before she came to work at the
University of Kentucky as a specialist in home economics extension. After serving for five years in rural Kentucky where she introduced hot school lunches in rural schools and courses in cooking and sewing in elementary and high schools, she was promoted to serve as the head of the department of Home Economics in the College of Agriculture in 1913. She was the first dean of the university's new College of Home Economics that was formed in 1916. Sweeney wrote that this step in moving the Home Economics department into a separate college was "the largest and most progressive step that has been taken in the interests of Kentucky women." She opined that a graduate from the new college would equally "rank with the man who takes his degree in law or medicine." A year later, the new College of Home Economics at the University of Kentucky was reabsorbed back into the College of Agriculture and under the leadership of a male dean. In 1917 Sweeney was appointed to be the chair of home economics for the U.S. Food Administration in Washington D.C. where she trained citizens about rationing food during wartime. She left with her sister Sunshine Sweeney in the fall of 1917 to work as canteen workers with the U.S. Army in France with the YMCA and the Army of Occupation in Germany. In 1920 Sweeney left to become Dean of Human Ecology at Michigan Agriculture College (now
Michigan State University), and in that same year was elected president of the
American Home Economics Association, which had been started in 1909 by
Ellen Swallow Richards. She returned to the University of Kentucky in 1923, but in 1925 left to become the Physical Growth and Development department chair of the Merrill Palmer School (later Institute) in Detroit, Michigan. She worked with the American Red Cross and the Detroit Public Schools to improve the care and nutrition of children living in the city, focusing heavily on the education of juvenile girls who were sent to detention homes or were studying at continuing education schools. A model for child development laboratories, the research and model programs coming out of this institution eventually led to the development of national standards for the federal
Head Start Program. By 1928, Sweeney became assistant director and recruited the school's only black student, Ethel Childs Baker, during an absence by the founding director, Edna Noble White. There Sweeney continued her work in research, teaching and writing about nutrition and child development until her retirement in 1946. In 1939 she spent three months in India learning the customs and government. She received a U.S. Army citation for bravery during World War II. After the war, Sweeney served as the North American Delegate to the International Missionary Conference in Madras, India. The All-India Women's Conference and the Tata Institute of Social Sciences invited her to return to India in 1948, and the
U.S. Department of State's Department of International Exchange of Persons supported her trip as a consultant in partnership with Agricultural Missions, Inc. In addition, she worked in China as a consultant on child welfare. Sweeney also taught at
Mississippi Southern College,
Hattiesburg. In 1958, the University of Kentucky Home Management House at 644 Maxwelton Court was named for Sweeney. Senior women would live in the house for six weeks to learn how to use modern appliances. Mary E. Sweeney was named to the Hall of Distinguished Alumni at the University of Kentucky in February 1965. ==Organizations==