Eragrostis is a large genus of grasses in subfamily Chloridoideae of the Poaceae. Recent phylogenetic analyses have suggested that the group may not be monophyletic, and there are a number of segregate genera that may be better placed within Eragrostis. We have used molecular sequence data from the plastid locus rps16 and the nuclear gene waxy from a broad sample of Eragrostis species and representatives of six of the seven segregate genera to address these issues. We find that Eragrostis is a monophyletic group with the inclusion of four segregate genera: Acamptoclados, Diandrochloa, Neeragrostis, and Pogonarthria. The placement of Cladoraphis and Stiburus is uncertain. Thellungia does not belong in Eragrostis and is actually more closely related to Sporobolus.