Zeralda Wallace became a leading member within her church. She convinced many of the leaders of the congregation to change the practice of offering fermented wine as part of the communion service. She and others worked to convince local politicians of the evil of alcohol in the 1870s and 1880s, and was one of the first leaders of the newly-formed Women's Christian Temperance Union of Indiana. This effort placed women like Zeralda Wallace in the public sphere. It also led to Wallace becoming a colleague of leading women and future advocates of equal suffragists such as Frances Willard.
Wallace presented a petition of over twenty-one thousand Indiana residents who supported temperance to the state legislature in 1875. After being rudely received by many of the male legislators, and after years of attempting to convince male political leaders to support their cause with limited results, Zeralda Wallace and other Indiana women increasingly supported equal suffrage for all citizens. In 1878, women met at Zeralda Wallace's home and formed the Equal Suffrage Society of Indianapolis. In 1880, Wallace testified in favor of equal suffrage for women before the United States Senate Committee on the Judiciary.