The Nearctic species of the genus Trixoscelis Rondani are revised. Thirteen new species are described, seven new combinations and three new synonyms are proposed, and three species groups are characterized. Keys to the 38 known species are provided. Diagnoses, detailed distributional data for the species of the genus, notes on the biology, and illustrations (photographs and drawings) are included to assist species identification. A phylogenetic analysis was performed to test the monophyly of the genus Trixoscelis and the included species groups. The ingroup includes a total of 38 exemplar species. Outgroup sampling includes the following exemplar genera: Neossos, Waterhousea, Fenwickia, Aneuria, and Xenura. Analyses, including implied weighting, recovered a monophyletic Trixoscelis and species groups if the Mongolian genus Paratrixoscelis is included within Trixoscelis
