The effect of solid‐solution atoms on the thermal‐expansion anisotropy of some oxides has been studied as part of a program directed toward the prediction of the thermal‐expansion coefficients of single crystals and single‐phase and polyphase ceramic bodies. The importance of solid‐solution atoms in determining the thermal‐expansion anisotropy of rutile, SnO2, corundum, and Cr2O3 solid solutions has been demonstrated. Vanadium additions to rutile are particularly effective in reducing thermal‐expansion anisotropy. The thermal‐expansion anisotropy was determined by X‐ray diffraction techniques in the temperature range room temperature to 1000°C. Information relating to the extent of solid solution of vanadium in rutile is presented. Research in this area may be important because reduction of thermal‐expansion anisotropy can prevent the formation of microcracks in ceramic bodies, thus leading to stronger bodies.