The Montana State Legislature is made up of two chambers, the Senate and the House of Representatives. The Constitution of Montana limits the size of the Senate to no fewer than 40 and no more than 50 members and the size of the House of Representatives to no fewer than 80 and no more than 100 members. Each house is responsible for choosing its officers, creating committees and establishing its own rules. The Montana Legislature meets for 90 days every odd numbered year, beginning the first Monday in January, or the following Wednesday if the first Monday is New Years Day. The first State Legislature convened on November 23, 1889, fifteen days after Montana became a state. Each following Legislature has been numbered sequentially.

The 15th Montana Legislature met from January 1st to March 1st, 1917, with an Extraordinary Session held February 14th to 25th, 1918. The leaders of the Senate were W.W. McDowell (D-President), and John Edwards (R-President Pro Tempore). The leaders of the House were Jas. F. O'Connor (D-Speaker), and Thomas Kehoe (D-Speaker Pro Tempore).

Sources: The Constitution of the State of Montana as adopted by the Constitutional Convention March 22, 1972, and as ratified by the people, June 6, 1972, referendum no. 68, http://leg.mt.gov/bills/mca_toc/Constitution.htm; "Organization of the Montana Legislature," The Montana Legislature, http://www.leg.mt.gov/css/About-the-Legislature/organization.asp; “Montana Legislative Leadership 1889 – Present” http://leg.mt.gov/css/About-the-Legislature/Facts-and-Statistics/leadership-through-history.asp