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Fire is a natural ecological process that shifts dominance from woody vegetation to herbaceous vegetation in big sagebrush plant communities. Historically, infrequent fire created mosaics of differing levels of sagebrush and herbaceous dominance across large landscapes. This provided a wide range of habitats that met the needs of many different species. Fire regimes have changed dramatically over the last century in big sagebrush communities. High elevation big sagebrush plant communities are experiencing longer fire return intervals, which allow conifer encroachment. Low elevation big sagebrush communities invaded by exotic annual grasses are experiencing more frequent wildfires. These fires often burn into adjacent un-invaded big sagebrush communities and facilitate exotic annual grass spread and subsequent dominance of these communities. Low elevation sagebrush communities need less frequent fire to limit the expansion and dominance of exotic annual grasses. In contrast, high elevation big sagebrush communities need fire re-introduced to halt and reverse conifer encroachment and to provide a diversity of habitats. However, the wide spread loss of sagebrush habitat and declines in sagebrush-associated wildlife species has resulted in a mentality that fire should not be re-introduced because of the short-term loss of sagebrush. These two diverging fire management needs have created confusion and often contrasting views of fire's role in big sagebrush communities. Further complicating the issue is that some big sagebrush communities are threatened by both conifer encroachment and exotic annual grass invasion.  Invasive species, climate change, and anthropogenic development have altered the role of fire in the sagebrush ecosystem, but it remains an important ecological process that can promote diversity.