The Morgantown Energy Technology Center (METC) conducted a number of feasibility studies on the combustion and retorting of five oil shales: Celina (Tennessee), Colorado, Israeli, Moroccan, and Sunbury (Kentucky). These studies generated technical data primarily on (1) the effects of retorting conditions, (2) the combustion characteristics applicable to developing an optimum process design technology, and (3) establishing a data base applicable to oil shales worldwide. During the research program, METC applied the versatile fluidized-bed process to combustion and retorting of various low-grade oil shales. Based on METC's research findings and other published information, fluidized-bed processes were found to offer highly attractive methods to maximize the heat recovery and yield of quality oil from oil shale. The principal reasons are the fluidized-bed's capacity for (1) high in-bed heat transfer rates, (2) large solid throughput, and (3) selectivity in aromatic-hydrocarbon formation. The METC research program showed that shale-oil yields were affected by the process parameters of retorting temperature, residence time, shale particle size, fluidization gas velocity, and gas composition. (Preferred values of yields, of course, may differ among major oil shales.) 12 references, 15 figures, 8 tables.