The Greater Sage-grouse, Centrocercus urophasianus, is the largest grouse in North America. Its range is sagebrush country in the western United States and southern Alberta and Saskatchewan, Canada. The Gunnison Sage-grouse was recently recognized as a separate species, and the Mono Basin population usually considered to belong to the Greater Sage-grouse may also be distinct.

Adults have a long, pointed tail and legs with feathers to the toes. Adult males have a yellow patch over the eye, are greyish on top with a white breast, a dark brown throat and a black belly; two yellowish sacs on the neck are inflated during courtship display. Adult females are mottled grey-brown with a light brown throat and dark belly.

This species is a permanent resident. Some move short distances to lower elevations for winter. These birds forage on the ground. They mainly eat sagebrush, also insects and other plants. They are not able to digest hard seeds like other grouse. They nest on the ground under sagebrush or grass patches.

Sage-grouse are notable for their elaborate courtship rituals. Each spring males congregate on leks and perform a "strutting display". Groups of females observe these displays and select the most attractive males to mate with. Only a few males do most of the breeding. Males perform on leks for several hours in the early morning and evening during the spring months. Leks are generally open areas adjacent to dense sagebrush stands, and the same lek may be used by grouse for decades.

The numbers of this species are declining due to loss of habitat; their range has shrunk in historical times, having been extirpated from British Columbia, Kansas, Nebraska, Oklahoma, Arizona and New Mexico. Though the Greater Sage-grouse as a whole is not considered endangered by the IUCN, local populations may well be so. This species have been petitoned for listing under the Endangered Species Act. However, the US Fish & Wildlife Service, for political reasons, has refused to list them. In May 2000, the Canadian Species at Risk Act listed the Centrocercus urophasianus phaios, formerly found in British Columbia, as being extirpated in Canada.

The Greater Sage-grouse is probably quite vulnerable to the change towards more humid climate caused by global warming, which would reduce the semiarid sagebrush habitat. Subfossil bones e.g. from Conkling Cave and Shelter Cave of southern New Mexico prove that the species was present south of its current range at the end of the last ice age.