Twenty-five cotton samples were mercerized slack and at 95% normal length. The samples were tested for tenacity at 0- and 3.2-mm gage lengths, T0 and T1, respectively, and for specific area fineness A, immaturity ratio I, and percentage of maturity by the sodium hydroxide swelling method. The strength uniformity T1/ T0 was more highly correlated with the ratio of the tenacity of mercerized samples to the tenacity of untreated samples tested at 3.2-mm gage lengths than was either of the maturity measurements. However, when the effect of T1, which was used in both tenacity ratio and strength uniformity calculations, was removed by partial correlations, the tenacity ratio depended about equally on strength uniformity and maturity. Nevertheless, strength uniformity made the greatest contribution to equations for predicting tenacity ratio from raw stock measures.