Polyethylene terephthalate yarn is prepared by spinning under high stress conditions in the transition region between oriented-amorphous and oriented-crystalline undrawn yarns by selection of process parameters to form an undrawn yarn that is a crystalline, partially oriented yarn with a crystallinity of 3 to 15 percent and a melting point elevation of 2.degree. to 10.degree. C. The spun yarn is then hot drawn to a total draw ratio between 1.5/1 and 2.5/1 with the resulting properties: (A) a terminal modulus of at least 20 g/d, (B) a dimensional stability defined by E.sub.4.5 +FS