After earning her PhB, she joined the faculty at Wellesley College, a newly established private college for women in Wellesley, Massachusetts. Angell recommended her for the position, noting her talent for teaching. She first taught English rhetoric, and in 1881 became an instructor in history.Bates, Katharine Lee. (1922). Yellow Clover: A Book of Remembrance. New York: E. P. Dutton & Company. In 1883, she was promoted to full professor of history. Because Coman believed that economics could address social problems, she urged the Wellesley administration to offer courses on the subject, and in 1883, she taught the college's first political economy class. Coman was the first American woman to teach statistics and Wellesley became the only American women's college to offer statistics courses before 1900.
