We present an optical electric field measurement method for use in high density plasma discharges. The method is based upon the field induced second harmonic generation technique and can be used for localized electric field measurements with sub-nanosecond resolution in any gaseous species. When an external electric field is applied, a dipole is induced in the typically centrosym-metric medium allowing for second harmonic generation with signal intensities which scale by the square of the applied field. Calibrations have been carried out in atmospheric pressure room air, and a minimum sensitivity of 20 V/cm is demonstrated. Measurements have been performed with nanosecond or faster temporal resolution in atmospheric pressure room air as well as pressures down to 100 Torr.