The ingress of miscible mixtures of a good and a bad solvent (methyl ethyl ketone and ethanol) into poly(styrene) has been visualized using magnetic resonance imaging (MRI). The use of both H-2 imaging with selectively deuterated solvents and C-13-H-1 cyclic cross-polarization (CYCLCROP) chemically selective imaging with normal solvents allows the individual components of the solvent mixtures to be measured separately. The two solvents are found to ingress together. However, the spatial concentration profiles are markedly different. The methyl ethyl ketone profile shows a sharp solvent front at the interface between the swollen rubber and the noninvaded glass and has a high solvent fraction throughout the rubber. The ethanol profile shows that the ethanol fraction decreases smoothly across the rubber and approaches zero at the front. These results are explained in terms of a simple multicomponent diffusion model, wherein the diffusion of the bad solvent is enabled by the presence of the good solvent.