Chromatography and capillary electrophoresis can be effective tools for the detection and evaluation of interactions occurring in solution and at the interface between solutions and stationary phases. Though there have been very few reports on fundamental studies of nonaqueous chromatography and capillary electrophoresis, potential importance of nonaqueous media in these separation is obvious because such media possibly enhance the applicability and facilitate the understandings of solution and interfacial chemistry. In this paper, nonaqueous chromatography and capillary electrophoresis are reviewed principally from fundamental viewpoints.