Forest stand structure, understory composition, and tree seedling composition are described for eight permanent tenth-hectare plots established in Engelmann spruce/subalpine fir, western larch, and interior Douglas-fir forest cover types in northwestern Montana. Sites have been protected as examples of old-growth stands since the establishment of the Coram Research Natural Area in 1937. Plot data clearly illustrate a successional trend toward shade-tolerant conifers, placing old-growth stands at risk of loss from succession or catastrophic fire. Management issues associated with use of prescribed fire to maintain old-growth characteristics in natural areas are discussed.