This study is a taxonomic revision of Cryptantha subgenus Oreocarya (Boraginaceae), together with descriptions of species, synonyms, distribution maps, and discussions. The present treatment recognizes fifty-seven species and fourteen varieties, all separated by means of a comprehensive key. A history of the group, along with a discussion of the distribution, ecology, and phylogeny is presented. As a basis for the comparison of taxa much of the research has been concentrated on morphological variation in herbarium specimens. Particular attention has been directed to a study of pubescence types, branching patterns, flowers, calyces, and the fruit. The herbarium research has been correlated with extensive field observations and collections made throughout most of western North America.