Polymers tagged with pendant fluorescent groups are prepared by the (trans)amidation derivatization of pre-existing polymers having carbonyl-type pendant groups. Polymers having pendant amide groups wherein the amide nitrogen is substituted with fluorescent moieties, prepared by (trans)amidation derivatization, and polymers having pendant (sulfonated) napthalene moieties substituted to amide nitrogen are provided, with mer units of the Formula V :
wherein R 4 is C n H 2n and n is zero or an integer of from 1 to about 10, R 1 , R 2 and R 3 are independently hydrogen or a substituent other than hydrogen, wherein one of X 1 and X 2 is hydrogen and the other is an (alkylene) naphthalene having from 0 to 2 sulfonic acid substituents or salts thereof, or wherein X 1 and X 2 contain, separately or together, at least one organic fluorescent group.