Fibers from ginned cotton and from 16/2s yarn of seven cottons of different physical properties were tested as a bundle and as individual fibers in order to determine what changes in properties, if any, could be attributed to the mechanical processing. Determinations of tenacity, length array distribution, and crystal alignment revealed no consistent differences between the cottons before and after processing. The maturity of carded cottons was slightly lower. The weight fineness and breaking load of individual fibers were unchanged with processing, but elongation curves of processed fibers, with the greatest difference found for loads below 2 g.