In recent history, there has not been a more ecologically important event than the introduction of cheatgrass (Bromus tectorum) and red brome (Bromus rubens) into the Intermountain West. These grasses are very similar in ecology and history and are separated mostly by function of elevation. Both species are from the Mediterranean region, and both arrived in the Western United States about the same time (1880). Cheatgrass and red brome have greatly affected fire frequency and intensity, which has been detrimental to native shrubs and other perennials in these systems. Red brome may have had an even greater impact, in that it has readily invaded non-disturbed areas, has had great impact on fire sensitive shrub species, and, to this point, we have not identified adapted species native or non-native for rehabilitating burned areas. Introduction of cheatgrass and red brome in the West has wreaked ecological havoc on the areas they have invaded and will continue to affect structure, function, and management of these areas well into the future. This paper will detail the history and ecology of these two highly invasive species.