A method of making a plastic container having a threaded wide-mouth finish includes providing a preform having at least an exterior surface of molded polyester construction. The preform is placed in a mold cavity having a first portion for forming a container body, a second portion adjacent to the first portion for forming a cylindrical finish wall without threads, and a third portion adjacent to the second portion for forming a trim dome or moil. The preform is expanded within the mold cavity to form a one-piece intermediate product that includes a body, a cylindrical wide-mouth finish wall and a moil. After removing the intermediate product from the cavity, the moil is severed from the end of the finish wall. At least one thread is then formed on the finish wall by engaging the finish wall with at least one thread-forming tool, which may be heated to facilitate the forming operation.