Thermodynamic data, in conjunction with appropriate software for calculation of complex chemical equilibria, are finding wide application in many areas of materials design and development. In particular, there have been enormous advances in the thermodynamic modelling of alloy solution phases, whereby a knowledge of the underlying crystallographic structure of each phase is fundamental to a reliable representation of the thermodynamic properties and phase equilibria of a particular system of interest. With the aid of thermodynamic calculations, considerable time and costs can and are being saved in producing a material of the required composition and phase constitution required for a particular application. SGTE has been at the forefront in providing critically assessed thermodynamic data for alloy systems and has provided guidelines for the modelling of alloy phases of different types.