Toluene, carbon tetrachloride, and tetrahydrofuran (THF) sorption and desorption by polypropylene (PP) and 20% and 40% talc-filled PPs were studied, and the effects of the solvent presence on the structure and mechanical properties were measured. The diffusion coefficients were related to the affinity of each solvent for the PP and their molecular volume. Whatever the solvent, the rate of solvent uptake and the equilibrium sorption decreased as the talc content increased as a consequence of the impermeable nature and lack of effect on sorption of the talc particles. All the materials showed highly reversible plasticization by the solvents. The relative decrease in the modulus of elasticity and tensile strength was the same in unfilled and filled PPs. However, important ductility increases, not seen in the unfilled PP, were obtained in the composites as the solvent content increased, probably due to the presence of both cavitation and rubberlike behavior.