A METHOD AND APPARATUS FOR WINDING ENDLESS YARNS ON A SPOOL IS DISCLOSED, THE METHOD AND APPARATUS PROVIDING A WINDING HAVING A CONSTANT WINDING RATIO, I.E., A SOCALLED "PRECISION WINDING," WHEREIN THE NUMBER OF SPOOL REVOLUTIONS PER THREAD-GUIDE STROKE IN A CROSS WINDING ARRANGEMENT REMAINS CONSTANT. THE INVENTIVE METHOD AND APPARATUS IS APPLICABLE FOR WINDING AN ENDLESS YARN FED AT A CONSTANT SPEED ONTO A SPOOL DRIVEN AT ITS CIRCUMFERENCE BY A DRIVE CYLINDER. THE THREAD IS FED TO THE SPOOL VIA A GROOVED DRUM OR A THREAD-GUIDE OPERATED BY A GROOVED DRUM. THE DRIVE CYLINDER IS DRIVEN IN KNOWN MANNER AT A CONSTANT SPEED. YET, THE GROOVED DRUM ITSELF IS DRIVEN IN DEPENDENCE UPON AND AS A FUNCTION OF THE NUMBER OF ROTATIONS OF THE YARN SPOOL OR THE DIAMETER OF THE YARN SPOOL AND THUS A CONSTANT WINDING RATIO IS MAINTAINED.