Mature cotton fibers from diverse cottons were used to determine the relationship between the weight average molecular weight (Mw) of crystalline cellulose and fiber tensile strength. Cottons were grown at College Station, Texas and samples from three replications of Rowden, Lankart 57, Deltapine 90, and SJC-1 and duplicate samples of Garo Hill, Texas Marker-1 and Pima 5-6 were evaluated. The Mw of the crystalline cellulose from the secondary walls of the cotton fibers was determined by Gel Permeation Chromatography by the procedure described in the preceding abstract "Gel Permeation Chromatography of Crystalline Cellulose from the Secondary Wall of Intact Cotton Fibers." Fiber tensile strength was determined on HVI instrumentation in the laboratories of Cotton Incorporated. Tensile strength of the lines ranged from 13 to 39 g/tex and it was linearly associated (R2 = 0.89) to the weight average molecular weight of the crystalline cellulose.