The excess entropy measured in dilute solid solutions of Al&sngbnd;Ag, Al&sngbnd;Zn, and Pb&sngbnd;Tl is compared to a theoretical vibrational entropy model. This theoretical model is based upon the localized influences which solute atoms produce in dilute solid solutions. The excess entropy, of vibrational origin, is found to arise principally from the mass and valence differences between solute and solvent atoms. Use of various types of potentials is made to calculate the ``force constants'' between the impurity atoms and the nearest‐neighbor atoms in the solid solutions.