Caddo Lake State Park is a state park located in the piney woods ecoregion of East Texas. The park consists of 484 acres (196 ha) on Big Cypress Bayou, west of Caddo Lake itself, in Harrison County, near Karnack, Texas. The park opened in 1934 and is managed by the Texas Parks and Wildlife Department. There are two separate units, Caddo Wildlife Management Area and Caddo Lake National Wildlife Refuge, nearby.

Caddo Lake is a 25,400-acre (10,300 ha) lake and bayou (wetland) on the border between Texas and Louisiana, in northern Harrison County and southern Marion County in Texas and western Caddo Parish in Louisiana. The lake is named after the Caddoans or Caddo, Native Americans who lived in the area until their expulsion by the United States in the 19th century. The US forced most of them to move west to Indian Territory.