Abstract : The results of a theoretical and experimental investigation of laser- based diagnostic techniques for the measurement of electric fields in discharges are presented. A theoretical assessment made of those techniques most likely to be successful in electric-field measurements under various plasma conditions is discussed. The three techniques identified and subsequently tested experimentally were polarization spectroscopy of H-atoms, optogalvanic spectroscopy of Rydberg states, and laser-induced fluorescence of the BC1 radical. The most successful demonstration of the electric-field measurement involved the optogalvanic technique because of the high sensitivity of the Rydberg states to electric fields. Electric field measurements were made on a hollow cathode in the range 1800 to 200 V/cm.... Stark effect, Electric fields, Plasmas, Laser-Induced fluorescence, Optogalvanic, Optical diagnostics, Polarization spectroscopy, Positive-Column discharge, Hollow-Cathode.