Wallace's first efforts as a social reformer were tied to the temperance movement. On March 3, 1874, she was among the organizers of the Women's Christian Temperance Union of Indiana. Wallace was elected the Indiana chapter's first president, serving from 1874 to 1876, and also served as its president from 1879 to 1882. In November 1874 Wallace attended the national WCTU conference at Cleveland, Ohio, where she met suffragist Frances Willard. Wallace was described as a "calm" and "non-radical" activist. Her friend Willard later remarked, "A man of equal ability would have been entitled to lead a party or to organize a cabinet."