Noncovalent molecular interactions that may occur in dye-fiber systems are classified into the following categories based on the different forces between two molecules: Van der Waals interactions, electrostatic interactions between static molecular charge distributions, induction forces, charge transfer stabilization, and solvophobic or hydrophobic interactions. An introduction to chemical changes in fibers and dyes to maximize the desirable properties of dyeing systems addresses the uptake of anionic dyes by polyamide fibers, uptake of planar anionic direct dyes by cellulosic substrates, dyes that form covalent bonds with teh substrate (reactive dyeing), and dyeing nonionic disperse dyes on hydrophobic and hydrophilic fibers. Hydrophobic and aromatic pi-pi interactions play the major role in the dyeing of nylon fibers. In the direct dyeing of cellulosic substrates, aromatic residues in the dye are more likely to form hydrogen bonds with he substrate -OH groups than with themselves. 38 refs.