The national body of the League of Women Voters was founded February 14, 1920, by Carrie Chapman Catt, president of the National American Woman Suffrage Association, who spearheaded the founding of the League of Women Voters in anticipation of ratification of the 19th Amendment. Mrs. Catt saw the League as a way to educate newly franchised voters.

The first Montana League organizational meeting was held in Great Falls on April 26, 1920, and the groups made plans to establish by-laws for the Regional Convention, which was held in Butte on May 25, 1921. Mrs. A. F. Rice of Butte was elected president. The first convention established Montana League goals to "work toward efficient government, the good of public welfare in government, and international cooperation to prevent war." The League also adopted a policy of non-alignment with any political party, but allowed for support of specific legislation and policy. Another objective was to urge every woman to register to vote.

By 1952 local Leagues were active in Billings, Butte, Havre, Helena, Great Falls and Missoula, with a membership of approximately 300. On October 23, 1953, Irene C. Sweeny, National Organizer, met with 29 delegates from the six city Leagues to coordinate the local Leagues. Laura Nicholson was named State Chair of the Executive Committee. The League of Women Voters of the United States required a State League to conduct a State Government study, with each local League investigating some phase of government. The study culminated in publication of Know Your State, used for many years in Montana classrooms as a text. On April 20, 1957, the first State Convention was held in Butte. The State League celebrated its 40th anniversary at Council in Hamilton in May 1994.