An earlier published concept, showing correlations between the “average lattice energy” of glasses (i.e. their mean molar atomization enthalpy ΔAH at 298 K), the network dimensionalityD and some properties of different chalcogenide and oxide glasses, was used to interpret the transformation temperaturesTg of glasses containing fluorine or nitrogen instead of oxygen. A plot of Tgvs. ΔAH allows the comparison of completely different glasses from only one graph. Such a consistent evaluation of composition/property relationships is useful for the further improvement of fluoride and nitride glasses, which are important for applications in optics and telecommunications and as quality-limiting components in silicon nitride-based ceramics.