A new method of solvent classification is proposed based on the five system constants of the solvation parameter model for transfer of neutral compounds from the gas phase to solvent and hierarchical cluster analysis for identifying solvents with similar properties and for organizing them into selectivity groups. This method resulted in the classification of 36 common solvents used in chromatography into seven selectivity groups with four solvents (2,2,2-trifluoroethanol, N,N-dimethylformaide, dimethyl sulfoxide, and water) behaving independently. Except for water, the three organic solvents identified as independent are probably a consequence of the lack of other solvents with similar properties in the data set rather than a demonstration of unique solvent behavior. The classification scheme provides a logical approach for solvent selection as the first step in chromatographic method development. A similar approach using the solvation parameter model suitable for the transfer of neutral compounds between...