The interactions of four Argonne Premium coals (Pocahontas No. 3, Upper Freeport, Pittsburgh No. 8, and Illinois No. 6) with carbon disulfide (CS2), N-methyl-2-pyrrolidinone (NMP), and their mixtures (CS2/NMP) were studied using an inverse liquid chromatography technique, in which the coals provided the stationary phase. The capacity factor CF (the increment of the elution volume of the probe relative to the elution volume of a carrier solvent) of each reagent was determined using acetonitrile as the carrier solvent. For the Illinois No. 6 coal, the elution curve of NMP showed an extended tail, which is a behavior that is not observed with the other higher-rank coals. In contrast, CS2 gave a pronounced tail with all high-rank coals, reflecting the strong interaction of CS2 with all available interaction sites in these coals. Furthermore, the CF of CS2, measured in both the Pocahontas No. 3 and Upper Freeport coals, became significantly increased when injected along with NMP, which demonstrates the considerable enhancement that occurs in the interaction of CS2 with these high-rank coals in the presence of NMP. Dimethylformamide and pyridine produced a similar increase in the CF of CS2 in the presence of NMP; however, benzene did not. The increase in the CF values found among the mixed solvents parallels the enhancement that these same mixed solvents bring to the extraction yields of bituminous coals.