It has 34 members, representing districts with an average population of 181,000.

[1] Its members serve four-year terms, with half the seats being up for election every two years.

The Senate chooses a President Pro Tempore to serve in the absence of the lieutenant governor or when he shall have to exercise the office of governor of Missouri if there is a vacancy in that office due to death, resignation, impeachment, or incapacitation.

[2] Members of the Missouri General Assembly are prohibited from serving more than eight years in either the state house of representatives or state senate, or a total of sixteen years, due to statutory term limits.

[3] After the 2024 general election the party representation in the Senate was: Source:[4] Under Rule 25 of the Senate Rules, all committees are appointed by the President Pro Tem, who is currently Cindy O'Laughlin.