The basis for the 0.25 unit higher micronaire of El Dorado compared to Maxxa was investigated. Fiber samples from both replicated test plot samples and from bale lot sized tests were examined. Measurements of micronaire, fineness and maturity were made using the Spinlab 675, FMT III, Arealometer, AFIS L&D, AFIS F&M, HVI, NIRA, MANTIS and image analysis. All data showed El Dorado to have a higher micronaire resulting from a significantly higher maturity. Dispite the higher micronaire, El Dorado fiber had a smaller perimeter and therefore was a finer fiber. El Dorado fiber was finer at a 4.6 micronaire than Maxxa was at 4.1. Therefore, micronaire can not be generally used as a measure of coarseness. El Dorado also showed improved dyeability and fewer white specks than Maxxa which were likely ramifications of the higher fiber maturity.