Oligotylus Van Duzee, 1916, is revised to include 16 species from western North America, six of which were previously described and placed in Psallus Fieber. Habitus and male genitalic illustrations are provided for all Oligotylus species; scanning micrographs of the head, scent-gland evaporatory area, vestiture, and pretarsus are included for selected species; a key to the species is presented. Oligotylus is compared with Lepidargyrus Muminov, the latter group being represented in North America by a single introduced species, L. ancorifer (Fieber); it is also compared with Plagiognathus Fieber, which is diverse in North America, and Psallus Fieber, which has no species native to North America except possibly at very high latitudes. Included for L. ancorifer are illustrations of male genitalia, scanning micrographs of selected structures, and locality and host data. The male genitalia and host associations of Oligotylus are shown to be distinctive from those of Lepidargyrus, Plagiognathus, and Psallus. Oligotylus species all feed on woody perennials in the families Rhamnaceae, Rosaceae, Saxifragaceae, and occasionally Ericaceae. Extensive host documentation is provided.