Most counties in South Dakota are governed under Dillon's Rule and therefore are only empowered with the authorities explicitly provided in the state’s legislation. Historically, the role of counties has been to serve as an administrative arm of the state – providing courts and law enforcement, providing welfare, assessing property, collecting taxes, and conducting elections. Counties still perform these functions, as well as many others, through full-time elected officials including a board of county commissioners, county auditor, county register of deeds, county sheriff, county state’s attorney and county treasurer.

South Dakota counties have the authority to provide a number of services, including but not limited to county health departments, hospitals and fire departments. Additionally, counties are required to fund the construction and provide the services related to courthouses, jails and county roads. Counties do not have the power to provide most utility services and have limited zoning authority within their jurisdictions. South Dakota counties may also provide for community development, infrastructure improvements and the promotion of tourism. County commissioners have the statutory authority to institute and prosecute civil actions, manage and preserve county property, levy taxes authorized by state law and provide needed services to the community. Each county may enact, amend and repeal any ordinance or resolution that is necessary for it to carry powers into effect and may provide for the enforcement of ordinances.