Establishment of western larch (Larix occidentalis Nutt.) seedlings is favored by site preparation that reduces both the duff layer and the sprouting potential of competing vegetation. A cooperative study of the use of fire in silviculture in northwestern Montana provided conditions to research the effectiveness of prescribed burning of logging slash from May through October for seedbed preparation. Greatest duff reduction, nonconiferous root mortality, and soil heating occurred when water content of duff and of soil was lowest. Slash must be burned in the summer when the duff is dry to significantly reduce the organic mantle. However, duff on north-facing slopes dries more slowly than on other aspects, and frequent summer rainfall may prevent effective preparation of seedbeds on north slopes. Burning to prepare seedbeds for establishment of regeneration can be conducted over a wider range of time on east-, south- and west-facing slopes.