Studies have been made on the physical and chemical properties and worsted processing char acteristics of two fine and two medium wools. Each of the wools studied was found to have essentially the same basic physical properties when reduced to the same cross-sectional area and to have the same chemical composition. The average diameter or fineness of a wool lot is the most important characteristic of the wool insofar as the efficiency of manufacturing operations is concerned. By aging the wool at 70°F and 70% R.H., an improvement in spinning and weav ing was observed. Steaming the wool in the form of roving was found to have the same bene ficial effect on spinning as aging under normal room temperature conditions. The aging process appears to be related to the relaxation of those stresses to which the fibers are subjected in previous processing operations.