Technical Abstract: Small (<40.5-ha) patch fires or mechanical manipulations to reduce big sagebrush (Artemisia tridentata) cover has been suggested as a management option to improve sage-grouse prenesting and brood rearing habitat and provide a diverse habitat mosaic. We evaluated the effects of prescribed fire and wildfire on sage-grouse habitat in three Wyoming big sagebrush associations (Bluebunch, Thurber’s needlegrass, Thurber’s needlegrass-Idaho fescue). Response variables included vegetation cover, herbaceous productivity, yield and nutritional quality of forbs preferred by greater sage-grouse, and abundance of common arthropod orders. Wildfire eliminated all sagebrush and >90% of the perennial grasses on the Thurber’s association. On the Bluebunch association wildfire eliminated sagebrush, however most perennial grasses survived. The prescribed fire on the Thurber’s needlegrass-Idaho fescue association removed 95% of the sagebrush with most perennial grasses surviving. Habitat cover (shrubs and tall herbaceous cover (> 18cm height)) was 33-90% lower after burning compared to unburned controls. The removal of big sagebrush decreased structural cover and reduced or eliminated forage provided by big sagebrush for sage-grouse. This would be potentially damaging in sage-grouse year-round and wintering habitat. Burning reduced Wyoming big sagebrush forage production by about 450 kg/ha on the Thurber’s needlegrass-Idaho fescue association. Yields or cover of perennial forbs used by sage-grouse in their diets did not differ between burned sites and not burned sites in the Bluebunch and Thurber’s needlegrass-Idaho fescue associations. In the Thurber’s needlegrass association long leaf phlox was the only perennial forb to increase after fire. Pale alyssum, a non-native forb, was the dominant annual after fire in the Thurber’s needlegrass and Thurber’s needlegrass-Idaho fescue associations. Yields or cover of annual forbs used by sage-grouse in their diets increased temporarily after fire in the Bluebunch association. Although cheatgrass increased in the Thurber’s association it has remained a minor component of the post-fire community. The abundance of ants (Hymenoptera) decreased after fire while the abundance of other arthropods remained unaffected in the Thurber’s needlegrass-Idaho fescue association. The results indicate that prescribed fire will not improve habitat characteristics for sage-grouse in Wyoming big sagebrush steppe where the community already consists of shrubs, native grasses, and native forbs. Burning of Wyoming big sagebrush communities to enhance other species habitat requirements should minimize mortality of native perennial grasses and forb species, result in a mosaic pattern of burned and unburned patches, and avoid areas of critical habitat.