This publication is an account of the palms (Arecaceae) in the state of Sonora in northwestern Mexico. Six native palm species in three genera are recorded for Sonora: Brahea with four species, and Sabal and Washingtonia each with one species. Relationships and taxonomy within Brahea, especially B. elegans, remain unresolved. Brief botanical descriptions, taxonomic synopses, local names, identification keys, conservation status and recommendations, and distributional and ethno- botanical information are provided for each species. Basionyms and types are cited. Distributions are documented with citations of nearly all herbarium specimens known to us from Sonora. Many palm populations in this arid and semiarid region are threatened by development and in some cases over- exploitation. There is an urgent need for formal management and conservation action for local pop- ulations, although as a whole none of these species in Sonora are rare or immediately threatened.