Steele Creek Park, a large municipal park in Sullivan County in northeastern Tennessee, has had nearly continuous observations of natural history data from trained naturalists for more than half a century. Here, we present a herpetofaunal list of species for the park that comprises: 10 species of frogs, 11 species of salamanders, 2 species of lizards, 11 species of snakes, and 7 species of turtles. The inventory includes 10 species previously unreported in Sullivan County. We then compared the park data with increasingly larger land areas in eastern Tennessee to establish a regional species–area curve for herpetofaunal richness that could have predictive capabilities for similar sites in the southern Appalachians.