In December 1900, Duff ran for the Boston School Committee election and her victory made her the first woman from the Irish Catholic community. During those times, there were several laws and regulations placed in an order that forbid women from directly participating in state and municipal politics. Hence, Duff's election created a platform for change and can be understood within the larger movement for gender equality in politics and public life.
While a member of the Boston School Committee, Duff advocated for equal rights for women and equal opportunities for all of the city's children. She worked to promote educational opportunity for women seeking teaching positions. With the help of other committeewomen, she supported and eventually succeeded in the establishment of kindergartens and schools for girls despite opposition. Even after losing her position at the committee when it was reduced from twenty-four members to only five members, Duff continued to advocate for more opportunities for women.
To commemorate her contribution to the society, her house is part of the Boston Women's Heritage Trail. She supported allowing girls into Latin School, the creation of kindergartens, and updated textbooks. Her house is now part of the Boston Women's Heritage Trail.