A pulsed-gradient spin-echo NMR technique was used to measure the self-diffusion coefficients (D) of water and several different solute probe molecules in ternary poly(vinyl alcohol) (IPVA)-water-solute systems, as a function of PVA concentration (up to 0.35 g/mL). The self-diffusion coefficient of water decreased with increasing PVA concentration, in a manner consistent with the Mackie-Meares obstruction effect model, and was independent of the polymer molecular weight, degree of hydrolysis, or the presence of the solute probes. The self-diffusion coefficients of the solute probes (methanol, tert-butanol formamide, acetic acid, trimethylamine, tetramethylammonium cation, and poly(ethylene glycol) of molecular weight 400 and 4000) decreased with increasing PVA concentration and increasing probe size. The fi ee volume theory could be used to describe the self-diffusion of solute probes only. The dependence of all the probe self-diffusion coefficients on polymer concentration could also be described using a stretched exponential function of the form D = D-0 exp(-ac(n)u) proposed by Phillies. With increasing PVA molecular weight, the scaling parameter nu generally decreased while the scaling parameter alpha generally increased. The analysis permitted an estimate of the correlation length (xi), corresponding to the mesh size of the polymer network, which is found to decrease from 20-30 Angstrom in the semidilute regime to 4-6 Angstrom in the moderately concentrated regime and was independent of PVA molecular weight.