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Grindeliais among the most taxonomically challenging groups of North American composites. The genus as a whole has an amphitropical distribution, with approximately half of the species native to North America and Mexico and the remainder native to South America. We used DNA sequence data from the nuclear ribosomal ITS and ETS and chloroplast psaI-accDregions to revisit hypotheses on biogeographic history across the genus. Grindeliaas a whole is well-supported and is composed of two sister clades, one native to South America and the other native to North America including Mexico. The North American taxa constitute two clades that largely occur on different sides of the Continental Divide. The diverse radiation of Grindeliain the California Floristic Province appears to be most closely related to species from the Great Basin and Colorado Plateau and evidently descended from drought-adapted ancestors. Although Steyermark's hypotheses about the relationships of North American Grindeliaare not all supported, we did recover a clade corresponding to his Pacific radiation and many of the Mexican and Texan species that he hypothesized to be basal in the genus represent early diverging lineages in our trees. Dunford's cytogenetic data on the North American species of Grindeliawere also examined in a phylogenetic context.