Textile yarn comprising oriented, crystalline fibers of poly(tetramethylene terephthalate) characterized by an improved combination of properties including a liveliness index of at least 0.25, and a toughness of at least 0.50 g./denier. Also disclosed is crimped staple textile fiber comprising oriented, crystalline, poly(tetramethylene terephthalate) characterized by a liveliness index of at least 0.25 and crush recovery greater than 50 percent.