This report presents a Bureau of Mines study comparing the construction costs, leakage measurements, and predicted performance of different types of large stoppings built and tested in a room-and- pillar oil shale mine. The six full-sized structures (30 ft high by 55 ft wide) included both permanent and temporary stoppings and were fabricated using materials ranging from structural steel to coated brattice cloth. Leakage across each stopping was measured at differential pressures ranging up to 1.0 In w.G., Using both the brattice window method and sulfur hexafluoride (sf6) tracer gas. Blast air pressures resulting from a full-scale face blast of approximately 1,800 lb of ammonium nitrate-fuel oil (anfo) explosives were measured across two of the stoppings, and the pre- and post-leakage rates were compared for all the stoppings. Overall performance of the stoppings for production applications was evaluated using an operational model of a two-panel oil shale mine. Different combinations of temporary and permanent stoppings were evaluated based upon ventilation performance and construction and operating costs.