H-1 nuclear magnetic resonance (NMR) studies were carried out on solutions of blends of lightly sulfonated polystyrenes (PS-SSA; 5-15 mol % sulfonation) of molecular weight (MW) 12 000 and 100 000, with poly(methyl methacrylate-co-4-vinylpyridine) (PMMA-4VP) copolymers (11 mol %) of MW congruent-to 100 000. The process of coil overlap was monitored as a function of time by the acquisition of proton spectra, which showed the gradual disappearance of the original methoxy signal and the appearance of a new signal originating from the shielded methoxy protons. The contributions of the two species were separated using a deconvolution program. To propose a complete model for the coil overlap phenomenon, parameters that can influence the kinetics of the process were studied. The parameters included the ion content and the MW of the PS-SSA, the temperature, and the total polymer concentration. The study of these parameters showed that the overlap was occurring through a complex mechanism. It was determined that the true order (n(c)) for the shielding process was second-order, reflecting the early stages of the mixing process. At the stage at which a "ladder"-like complex is produced, the experimental data can best be represented by a kinetic expression containing two opposing first-order reactions.