Her approach contrasted with that of more conservative members of the Illinois Equal Suffrage Association like Grace Wilbur Trout, who preferred more quiet and diplomatic lobbying. In 1894, McCulloch and fellow members of the Chicago Woman's Club founded the Chicago Political Equity League to campaign for municipal suffrage. In addition to her suffrage work, McCulloch advocated for maternalist reform measures. For example, she championed the passage of a law in 1901 that gave women equal guardianship with their husbands over their children. In 1905, she helped raise the age of consent for girls from 14 to 16 years. McCulloch was elected Justice of the Peace in Evanston, Illinois in 1907 (and re-elected in 1909), making her the first woman elected to that office in Illinois. While a Justice of the Peace, she made national headlines by agreeing to conduct egalitarian marriage ceremonies in which she omitted the word "obey" from the ritualized words the woman was supposed to say; at that time, the man pledged to "love, honor and cherish" while the woman pledged to "love, honor and obey." In 1917, she was appointed as a master in chancery of the Cook County Superior Court. She became known for her advocacy in working to eliminate or modify marriage and divorce laws that discriminated against women, and she worked to create uniformity of such laws in all states. She was the legal adviser for the National American Woman Suffrage Association (which became the League of Women Voters in 1920 after passage of the 19th Amendment) and was its first vice president. She also served as the legal adviser for the National Women's Christian Temperance Union. McCulloch died of cancer in 1945 at the age of 82. Catharine W. McCulloch Park in Evanston is named for her.