There is an increasing demand for materials capable of withstanding ever-higher temperatures. However, because the difficulties associated with carrying out experimental investigations at very high temperatures are significant, the published information relating to the phase stability of potential refractory materials is, in many instances, still lacking. The work described in this paper attempts to rectify this deficit through the on-going development of a thermodynamic database for high-temperature materials based on carbides, nitrides, borides, and silicides. Because of technological requirements of high-temperature stability and strength, combined with lightness, these are the materials that come into question most frequently for high-temperature applications. In developing the present database, and to ensure reliability of its use, emphasis has been placed on the need to maintain the compatibility of data and modeling when assessing experimental data and estimating missing values. The methods used to achieve compatibility of published information are described and calculations of phase equilibria relevant to the industrial application of various refractory materials are presented. The similarity to, and the importance of the scientific background and published work of Ted Massalski for the work of the present author is stressed.