Results are reported on pilot retorting operations including: simulated modified in-situ (MIS) operations, aging of crushed shale, temperature measurement methods, intermittent retorting and recycled offgas. Field testing of retort operation and control is discussed. Model calculations of Rio Blanco No. 0 and No. 10 are summarized. The effects of using oxygen diluted by steam or carbon dioxide in MIS retorting are reported. (DC)