We propose a new classification of the grouse that brings their taxonomy into agreement with our molecular phylogenetic studies. Our analyses provide, for the first time, a robust estimate of the evolutionary history of these birds. These analyses are based on aligned sequences of 3,809 basepairs of five complete mitochondrial genes. Our classification does not require novel genera and generally results in the maintenance of accepted generic names. Only two mono- typic genera are required. We recognize the grouse as a subfamily, Tetraoninae, within the family Phasianidae. We recognize three tribes; these include a tribe (Bonasini, a new taxon) for the ruffed grouse Bonasa umbellus, a tribe (Tetrastini, a new rank) for hazel hens in the genus Tetrastes, and a tribe (Tetraonini, a new rank) for all the remaining species. We divide this last, derived tribe into five subtribes that correspond to 1) Falcipennina (a new taxon) for the sharp-winged grouse Falcipennis falcipennis, 2) Canachitina (a new taxon) for the New World spruce grouse in the genus Canachites, 3) Tetraonina (a new rank) for the capercaillies and black grouse in the genera Tetrao and Lyrurus, respectively, 4) Centrocercina (a new taxon) for the New World prairie and forest grouse in the genera Tympanuchus, Centrocercus and Dendragapus, and 5) Lagopodina (a new taxon) for the ptarmigans in the genus Lagopus. All the taxa in our classification, at all ranks, are monophyletic with bootstrap support of 95% or more.