A micromechanical analysis which is capable of predicting the nonlinear behavior of multiphase composites in which one or more phases are electrostrictive materials is proposed. In view of the nonlinear behavior of the electrostrictive constituents, an incremental procedure in conjunction with a tangential formulation is developed. As a result of the micromechanical analysis, the instantaneous electromechanical concentration tensor and thermal-pyroelectric vector are established. These readily provide the current electromechanical effective constants, coefficients of thermal expansion and the associated pyroelectric coefficients. Results are given that show the effects of electrical, mechanical and thermal loadings on the behavior of electrostrictive porous materials, and the capability for sensing by tagging of electrostrictives in a polymer matrix composite is illustrated.