The connection between CALPHAD models and Phase-Field models is discussed against the background of minimization of the total Gibbs energy of a system. Both methods are based on separation of a multiphase system into individual contributions of the bulk phases, which are described by appropriate models in composition, temperature, and pressure. While the CALPHAD method uses a global minimization of the total Gibbs energy, the Phase-Field method introduces local interactions, interfaces, and diffusion and allows for non-equilibrium situations. Thus, the Phase-Field method is much more general by its concept, however, it can profit a lot if realistic thermodynamic descriptions, as provided by the CALPHAD method, are incorporated. The present paper discusses details of a direct coupling between the Multiphase-Field method and the CALPHAD method. Examples are presented from solidification of technical Mg and Ni base alloys and some problems arising from common practice concerning thermodynamic descriptions in order-disorder systems.