The quasiharmonic approximation is used to calculate the Helmholtz free energyF. The interionic forces are represented by a deformation‐dipole model, which is parameterized self‐consistently. We give parameterized expressions forFthat can be used to predict the temperature and volume dependence of the thermodynamic properties of CsCl, CsBr, and CsI. These expressions forFare tested by comparing our predicted values for the heat capacityCPand the thermal expansion &agr; with experimental atmospheric‐pressure values. Good agreement is obtained. Predicted values forCV, &agr;,BT, the compression −&Dgr;V/V0, and the Gru¨neisen &ggr; at elevated pressures are given, as are zero‐pressure values for the logarithmic derivativeqT= (∂ln&ggr;/∂lnV)Tand the Anderson‐Gru¨neisen parameters &dgr;Sand &dgr;T.