The 15th Legislative Assembly of Ontario was in session from October 20, 1919, until May 10, 1923, just prior to the 1923 general election. The leading party in the chamber after the election was the United Farmers of Ontario. It formed a coalition government with 11 Labour MLAs and three Independent candidates of varying stripes. Most of the seats the United Farmers won were taken at the expense of the Conservative party, who had formed the government in the preceding assembly and would again regain power in 1923. Nelson Parliament served as speaker for the assembly.