AbstractCalculations are made to determine strain derivatives of static and high‐frequency dielectric constants of MgO, TlCl, and TlBr, using the two‐ion polarizable shell model. The calculated values of pressure derivatives of the static dielectric constant of MgO, TlCl, and TlBr are in good agreement with the experimental values. A reasonable agreement is seen between the calculated values and the measured values of strain‐optical constants for MgO. Strain‐optical constants are also calculated for thallous halides. Anisotropy in the polarizability of ions arising from strain is fairly accounted for by the shell model through the large contributions from overlap