The South Dakota State Legislature is the legislative branch of the government of South Dakota. It is a bicameral legislative body, consisting of the South Dakota Senate, which has 35 members, and the South Dakota House of Representatives, which has 70 members. The two houses are similar in most respects; the Senate alone holds the right to confirm gubernatorial appointments to certain offices. In addition, the Senate votes by roll call vote, whereas the larger house uses an electronic voting system.

The structure of the government of South Dakota is based on that of the federal government, with three branches of government: executive, legislative, and judicial. The structure of the state government is laid out in the Constitution of South Dakota, the highest law in the state. The constitution may be amended either by a majority vote of both houses of the legislature, or by voter initiative.