Reactions of various monoepoxides and diepoxides with diethylaminoethyl (DEAE) cellulose in the absence and presence of external catalysts have been studied. In the absence of additional catalysts, many epoxides which did not react with the unmodified cotton reacted with DEAE-cotton. Others, which reacted with unmodified cotton in the presence of external bases, imparted different properties when catalyzed by the builtin tertiary amino groups of DEAE-cotton. For example, epichlorohydrin reacted with DEAE-cotton to produce a fabric with excellent conditioned recovery, good wet recovery, and strong-base anion exchange properties. The same epoxide imparted only wet crease recovery to cotton when the reaction was catalyzed by external bases. Phenyl glycidyl ether and styrene oxide reacted with DEAE-cotton to produce a fabric with twentyfold improvement in resistance to flex abrasion. With 8% aqueous NaOH as an external catalyst, the DEAE-cotton displayed greater reactivity with all epoxides than did the unmodified fabric. DEAE-cotton–diepoxide reactions with added base catalyst generally resulted in a decrease in the conditioned recovery angle and an increase in the wet recovery angle. When Zn(BF4)2 was used as an additional catalyst, again the DEAE fabrics displayed the greater reactivity toward the monoepoxides; but the unmodified cotton was more reactive toward the diepoxides than was the DEAE-cotton. The Zn (BF4)2–monoepoxide-treated DEAE fabrics had higher wet recovery angles but lower dry recovery angles than the corresponding epoxide-finished control cottons. Butadiene diepoxide was the only diepoxide investigated which imparted higher dry recovery angles to the DEAE-cotton than to the unmodified cotton control in the presence of Zn(BF4)2. Tertiary amino groups in DEAE-cottons act as an internal catalyst for the opening of the oxirane rings, direct the site for reaction in the absence of additional catalysts, and react with some epoxides to form quaternary nitrogen groups.