We assessed the effects of livestock grazing on vegetation and small mammals in semiarid habitat at a site in northeastern Nevada. Habitat within a fenced exclosure that had been protected from grazing for more than 50 years supported more vegetation and had greater plant diversity compared to habitat immediately outside the exclosure. Likewise, species richness and abundance of small mammals were greater in ungrazed areas. Results suggest that grazing regulation in recent decades may account for some of the changes seen in regional plants and small mammals over the past century. The incorporation of long-term exclosures in a comparative framework permits differentiation of the direct effects of grazing on biotic communities and thus provides a reference point for assessing the influence of grazing relative to other factors in the interpretation of historical change.