Montgomery worked on social reforms in the United States, especially those to benefit women. In 1893, she joined with Susan B. Anthony, the Activist for civil rights who was nearly 40 years older, in forming a new chapter of the Women’s Educational and Industrial Union (WEIU) in Rochester. Montgomery served as President from 1893-1911, which "enabled her to exert broad influence in the city's social and political affairs." She and Anthony worked together for more than a decade on women's issues in Rochester. Following the Example of chapters in Buffalo and Boston, the WEIU of Rochester served poor women and children in the city, which was attracting many Southern and Eastern European rural immigrants for its industrial jobs. The WEIU also founded a legal aid office, set up public playgrounds, established a "Noon Rest" house where working girls could eat unmolested, and opened stations for mothers to obtain safe milk, which later developed as public health clinics. It developed as one of the most important Progressive institutions in the city.