Settable drilling fluids that comprise an aqueous-based drilling fluid and cement kiln dust. Methods of cementing in a subterranean formation that comprise providing a settable drilling fluid comprising an aqueous-based drilling fluid and cement kiln dust, introducing the settable drilling fluid into a subterranean formation, and allowing the settable drilling fluid to set in the subterranean formation. Methods of converting an aqueous-based drilling fluid to a settable drilling fluid that comprise providing the aqueous-based drilling fluid, and adding cement kiln dust to the aqueous-based drilling fluid to form the settable drilling fluid. Methods of drilling a well bore and cementing a well bore that comprise drilling a well bore, circulating an aqueous-based drilling fluid in the well bore during the step of drilling the well bore, adding cement kiln dust to the aqueous-based drilling fluid to form a settable drilling fluid, and allowing the settable drilling fluid to set in the well bore.