Mobile order theory provides an alternative thermodynamic approach for mathematically describing associated solutions. The basic model expresses the equilibrium condition in terms of the time fractions for the time schedule that a given molecule in an ensemble is “free” or “bonded”, and not in terms of the concentrations of the various associated species believed to be present. This review article discusses the thermodynamic basis of Mobile Order theory, and critically examines the model`s applicability using published vapor-liquid equilibria (VLE), solid-liquid equilibria (SLE) and excess enthalpy data for binary and ternary systems containing alkane and alcohol cosolvents. Also presented is the application of Mobile Order theory to aqueous solubility predictions of crystalline organic nonelectrolyte solutes.