Apparatus and method for making a molded plastic article having a stretched and crystallized neck finish. In one embodiment, a series of platforms are carried by a conveying apparatus for transporting a series of molded plastic articles along a predetermined path of travel through one or more treatment stations. At a finish widening station, the molded article, having a relatively wide and thin-walled blow-molded body portion, and a relatively narrow and thick-walled unexpanded neck finish portion, is positioned to enable insertion of a mandrel into an open top aperture of the finish portion to widen the finish. The mandrel may include a lower heated tapered portion for expanding the finish, and an upper cooled body portion on which the expanded finish may be cooled. The article may then be sent to a finish crystallizing station having a heating device that heats the widened finish portion for a time and temperature selected to crystallize at least a portion of the widened finish. A sizing mechanism positionable in the widened finish supports the finish during crystallization.