Bagley and others formed the Lowell Female Labor Reform Association, advocating for worker rights.
On December 1, 1844, Sarah Bagley met with five other women at the Anti-Slavery Hall in Lowell, Massachusetts, to establish the Lowell Female Labor Reform Association. This was one of the first successful working women organizations in the United States. They campaigned for labor rights, notably the ten-hour workday, setting a precedent for future labor movements and highlighting women's active role in social reforms.