Although at the present time there is no commercial production of shale oil in the United States, considerable effort has been directed toward the development of an oil shale retorting process adapted to the type of oil shale, as well as to the economic conditions prevailing. Shale oil can be produced by simple pyrolysis, but the scale of production necessary, the relatively small yield of oil, and the location of the principal deposits in an area of limited water supply present sizable engineering problems. These conditions dictate that the successful Americal oil shale process has high unit capacity, efficient energy utilization, and uses little or no water. This paper traces the development work which las led to the construction and operation of such an engineering plant.