A continuously recording X-ray diffractometer was used to study changes in the crystalline structure of cotton fibers subjected to a wide range of chemical and physical treatments. These included combinations of mercerization and bleaching and crosslinking utilizing either wet crosslinking with formaldehyde (Form W) or dry crosslinking with dimethylol dihydroxy ethylene urea (DMDHEU) or Citric Acid (CA). Results indicate that crosslinking of bleached cotton does not change the crystalline nature of cotton, but does increase its degree of crystallinity. Cellulose II structure in mercerized cotton is very similar to that observed in pure viscose (Fortisan). Crosslinking of mercerized cotton changes the crystalline nature of the fiber in that the degree of crystallinity of Cellulose II (mercerized cotton) is diminished while there is an appearance of certain Cellulose I (native cotton) characteristics.