X-ray fluorescence is a rapid, nondestructive method of analysis that shows potential for the detection of immature cotton fiber and associated dyeing defects in fabric. Elemental analyses by x-ray fluorescence were evaluated as a cotton fiber maturity marker. Fiber calcium concentrations were monitored in Deltapine 50 at three stages of boll development; 20, 31, and 45 days postanthesis. Relative calcium concentrations decreased during the secondary wall stage of fiber maturation and showed an inverse relationship to micronafis values. The performance of the method will also be evaluated for other cotton varieties. Sulphur concentrations in the three types of samples, dyed using particular direct dyes, will also indicate the extent of development of the secondary wall by tracking dye uptake. Development of a quantitative dye test for mote detection and maturity classification is in progress.