Devils Postpile National Monument is 319 ha in size, located in Madera County, California, on the western slope of the Sierra Nevada at an average elevation of 2280 m. Though small in size, the monument supports diverse habitats, including forests, chaparral, riparian corridors, meadows, seeps, and ponds. In 2001, the National Park Service conducted a survey to 1) inventory the vascular flora and document with vouchered specimens; and 2) describe the distribution and abundance of species of special management concern (rare and/or non-native). Methods coupled a species-level inventory with vegetation mapping, covered an estimated 70 percent of the monument's surface area, and combined broad and targeted search strategies. Survey results yielded a 121 percent increase (from 169 to 373) in the number of documented plant taxa, representing 60 families and 199 distinct genera. Forty-five percent of species were clustered within six families: Asteraceae, Poaceae, Cyperaceae, Brassicaceae, Onagraceae, and Boraginaceae. The survey found three rare and eight non-native taxa previously unknown from the monument and documented nine potential range extensions. Rare species included Cinna bolanderi (new county record), Hulsea brevifolia, and Mimulus laciniatus. Localized infestations of the non-native and invasive Cirsium vulgare were discovered. Control measures for this species were initiated during the field season and continued in subsequent years.