The Fifteenth Wisconsin Legislature convened from January 8, 1862, to April 7, 1862, in regular session, and re-convened from June 3, 1862, through June 17, 1862. The legislature further convened in a special session from September 10, 1862, through September 26, 1862. This was the first legislative session after the expansion and redistricting of the Senate and Assembly according to an act of the previous session. The Senate grew from 30 to 33 seats; the Assembly grew from 97 to 100 seats.