It was formed on November 25, 1897, when the Spanish government of Prime Minister Práxedes Mateo Sagasta granted autonomy to the archipelago, creating a House that was composed of 32 members.

[2] In addition to the House, there was also an Administrative Council of 15 members, eight of whom were elected by a "Colegio de Compromisarios" and the other seven were named by the Governor General in representation of the Spanish monarch.

After Puerto Rico was ceded to the United States on July 25, 1898, as part of the Spanish–American War, a military government was imposed archipelago.

[3] This was until April 12, 1900, when the U.S. Congress approved the first civil government for Puerto Rico under the federal Foraker Act.

The Senate retains the exclusive power to extend its consent to appointments to government offices made by the governor (judges, cabinet secretaries and others) as stated by law or Constitution.

477 of September 23, 2004 provided for a referendum to be held on July 10, 2005, in which Puerto Rican voters were to indicate if they favored changing the Legislative Assembly to a single house, or maintain the bicameral legislature established by the 1917 Jones Act, which had been retained (with modifications) by the 1952 Constitution of the Commonwealth of Puerto Rico.

In the unicameral referendum held on July 10, 2005, Puerto Rican voters approved a mandate for the Legislative Assembly to hold a second referendum on the constitutional amendment that would establish unicameral legislature by 456,267 votes in favor, versus 88,720 against; voter turnout was only 22.6%, the lowest turnout figure in Puerto Rico's electoral history, vastly below the 81.7% that had gone to the polls just a few months earlier for the general election.

[7][8][9] Another referendum was scheduled for July 2007 to approve the specific amendments to the Constitution of Puerto Rico that are required for the change.

However, the Supreme Court of Puerto Rico ruled in June that it could not force the Legislative Assembly to initiate a constitutional amendment process to become a single chamber legislature.