Abstract: This invention provides methods by which any staple fiber or continuous filament fiber can be stretch processed similiar to continuous filament fiber stretch processing methods heretofore used, in that the fiber's internal molecular structure is oriented along the fiber strand axis, except substantially twisting as well as substantial stretching forces are employed. With only the simple continuous and simultaneous application of a single dynamic stretching stress, and a single dynamic twisting force, that is correct and precisely controlled relative to each other and to its input flow rate, every individual fiber is effectively and uniformly stretch processed. Such individual fiber's net strength properties gain and desirable quality characteristics improvement as well as their continuous cross-sectional uniformity are substantially enhanced for their greater utility, as are fabrics and other products produced from such treated fiber.