Laboratory studies to evaluate the use of electricity for fracturing various grades of Colorado oil shale were started in 1964. Breakdown voltages varied greatly from one grade of shale to another, ranging from a minimum of 300 V to a maximum of 15,000 V. With few exceptions, the shale samples were readily fractured at relatively low current levels. On the basis of encouraging results obtained in the laboratory, experiments were expanded to field tests to study electrical characteristics of oil shale when subjected to overburden pressure. These tests generally confirmed the laboratory experiments. Fracturing was accomplished at all electrode spacings used. The spacings varied from 3 to 129 ft. Based upon results obtained in these field experiments, additional fracturing tests were conducted in four shallow wells drilled in an oil shale formation. Some new permeable zones were created between wells. The induced permeability was improved by detonating two conventional nitroglycerin wellbore shots in one of the wells.