Electrostriction is the basis of electromechanical coupling in all insulators. The quadratic electrostrictive strain x(ij) associated with induced polarization components P-k and P-l is given by x(ij) = Q(ijkl)P(k)P(l). Two converse electrostrictive effects may also be defined. In this paper, some trends in structure-property relationships that govern electrostriction are identified,, along with the problems that limit our understanding of this fundamental electromechanical property. Electrostrictive coefficients range from the similar to 10(-3) m(4)/C-2 in relaxer ferroelectrics to similar to 10(3) m(4)/C-2 in some polymers. High-sensitivity techniques, such as interferometry or compressometry, are necessary to accurately measure electrostrictive effects in most insulators. But even in low-K dielectrics, electrostrictive stresses may initiate breakdown in high-field environments such as microelectronic components with small dimensions, high-voltage insulators, or in high-power lasers. In polymeric materials, charge injection mechanisms may produce local electric field concentrations that can cause large electrostrictive strains. The electromechanical properties in polymers have also been observed to vary with the thickness of the specimen. A brief description of the anharmonic nature of electrostriction and its frequency dependence is included.