This talk will provide a brief overview of the activity at GE Global Research on phase diagram determination, assessment and application. Earlier major phase diagram activity at GE includes the compilation of the four-volume “The Handbook of Binary Phase Diagrams” by Dr. William Moffatt. Much of the phase diagram research in recent years has been on systems related to Ni-base superalloys, coatings, Nb silicide-based composites, and precious metal alloys. The interplay of phase diagram research and alloy development will be illustrated. The development of the diffusion-multiple approach allowed us to achieve orders-of-magnitude increase in efficiency in phase diagram determination. We are also using thermodynamic modeling (the CALPHAD approach) routinely to help us design new alloys and processes. Examples will be shown to illustrate progress in these areas.