The Board of Trustees elected Miss Margaret Mann as principal in 1849, hoping she possessed the qualities to continue Miss Cate's improvements. After only a brief tenure, however, the Board noted that her “lack of serious religious commitment” in the Seminary caused them great concern. Although Wheaton Seminary was non-sectarian, it was committed to Christian spiritual and moral concepts, and expected them to be emphasized in the curriculum and leadership. After the board searched for and found a principal that they believed would provide these qualities, they essentially forced Miss Mann to resign.
One obstacle to Miss Mann's success in her one-year tenure was the construction of a new Seminary Hall, paid for with Laban Morey Wheaton's gift of $10,000. The noise, dirt, workmen, and general disruption must have made it difficult to maintain order and discipline.
Margaret Mann married Mr. Thomas Rice. Like all the other principals, she returned to address the Seminary at its 50th Anniversary celebration in 1885.