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Based on the application of OB considerations (Part I) to various major thermal barrier coating (TBC) compositions and two types of important calcium-magnesium-alumino-silicates (CMAS)desert sand and fly ashthe 2ZrO(2)Y(2)O(3) solid solution (ss) TBC composition, with high CMAS-resistance potential, is chosen for studying molten-CMAS/TBC interactions. It is demonstrated that 2ZrO(2)Y(2)O(3)(ss) air plasma sprayed (APS) TBCs are highly resistant to high-temperature attack by both sand-CMAS and fly-ash-CMAS. Despite the differences in the compositions of the two CMASs, the overall CMAS-attack mitigation mechanisms in both cases appear to be similar, viz reaction between 2ZrO(2)Y(2)O(3)(ss) APS TBC and the CMAS, and the formation of main reaction products of Y-depleted c-ZrO2 and nonstoichiometric Ca-Y apatite. Large differences in the OBs () between the 2ZrO(2)Y(2)O(3)(ss) and the CMASs are good predictors of ready reaction between this TBC and these CMASs. While the details of the CMAS-mitigation mechanisms can depend critically on various other aspects, the OB difference () calculations could be used for the initial screening of CMAS-resistant TBC compositions.