The electro‐optic Kerr effect and its wavelength dispersion have been measured in glasses representing several compositional systems. The measured Kerr effect was found to be large for glasses having large refractive indices, including: (i) glasses containing high concentrations of the heavy metals Pb, Bi, and Tl; (ii) glasses with high Nb, Ta, and Ti content; and (iii) tellurite glasses. Comparison of the third‐order nonlinear susceptibility, &khgr;eff(&ohgr; = &ohgr; + 0 + 0), obtained from the measured electro‐optic data, to values estimated from literature values of the optical frequency value, &khgr;eff(&ohgr; = &ohgr; + &ohgr; − &ohgr;) suggest an opposition of the electronic and nuclear contributions to the low‐frequency electro‐optic effect for the glasses containing Ti, Ta, or Nb.