The 1st Mississippi Legislature met between October 6, 1817 and February 6, 1818, first in Washington and then in Natchez, Mississippi.
Elections were held on September 17, 1817. Senators and representatives first convened in Washington, Mississippi, between October 6 and October 9, 1817. They then met in Natchez, Mississippi, on December 8, 1817. The Senate adjourned on February 4, 1818.
Senators were to be elected to staggered three-year terms. Lots were drawn to determine how many years each senator's term would last (including the first session) before re-election.
Two senators, Duncan Stewart and David Dickson, resigned during the recess in between October and December. Joseph Johnson was sworn in to replace Stewart (who had been elected lieutenant governor) on December 9, 1817. Stewart, who was sworn in on December 9, 1817, became the ex officio president of the Senate. Nathaniel Wells was sworn in to replace Dickson on January 2, 1819. The House adjourned on February 6, 1818.
The House met alongside the Senate on October 6, 1817. On that day, Thomas Barnes of Claiborne County was elected Speaker of the House. Then, non-representatives Peter A. Vandorn and John Lowry were elected to the offices of House clerk and doorkeeper respectively. One representative, Benjamin Bullen, resigned in between the October and December meetings. Cowles Mead was sworn in to replace Bullen on December 8, 1817.