MacLean's teaching and administrative work began at
Shimer College, then known as the
Mount Carroll Seminary and located in
Mount Carroll, Illinois. She worked at Shimer from 1894 to 1896, serving as instructor of Latin and
lady principal, a position approximating the later role she served as
Dean of Women. Her sister, Mildred, also worked at Shimer. The MacLean sisters remained in contact with the Shimer community into their retirement in the 1930s. As a woman, MacLean was largely excluded from conventional academic positions in her field. Unlike male students, she was not hired into the sociology department, even though she "far surpassed the productivity of her male peers". Her initial teaching posts after her graduate study were at
Royal Victoria College in Montreal, where she taught from 1900 to 1901, and at Stetson University in Florida, where she taught sociology from 1901 to 1903. She taught correspondence courses in the University of Chicago's Home Study Department from 1903 to a few months before her death in 1934. In addition, she taught as a professor of sociology at
Adelphi College from 1906 to 1916, and at the YWCA National Training School from 1903 to 1916. In the Home Study Department at the U of C, MacLean worked alongside other notable women sociologists, including
Edith Abbott and
Sophonisba Breckinridge. She taught courses on subjects including rural life, social technology, and immigration. In the course of her career as a correspondence-school professor, she taught 799 students. ==Sociological and writing career==