The oribatid family Eremaeidae is represented in North America by two genera, Eremaeus and Eueremaeus, both widely distributed throughout the Palaearctic and Nearctic regions. In North America species in both genera are found in moist to arid habitats from New Mexico to the High Arctic. Reproduction is sexual, and both immatures and adults feed mainly on fungi.Revised diagnoses are presented for the Eremaeidae and genera Eremaeus and Eueremaeus. Eighteen species of Eremaeus, of which 14 are newly proposed, and 24 species of Eueremaeus, of which 15 are newly proposed, are recognized. Identification keys are provided for the world genera of Eremaeidae, and for adults of Eremaeus and Eueremaeus of North America. All but one North American species of these genera are described, and their geographical distributions mapped.North American Eremaeus species include E. appalachicus sp. no v., E. boreomontanus sp. nov., E. brevitarsus (Ewing), E. californiensis sp. nov., E. gracilis sp. nov., E. grandis Hammer, E. kananaskis sp. nov., E. kevani sp. nov., E. megistos sp. nov., E. monticolus sp. nov., E. nortoni sp. nov., E. occidentalis sp. nov., E. oresbios sp. nov., E. plumosus Woolley, E. porosus sp. nov., E. salish sp. nov., E. translamellatus Hammer, and E. walteri sp. nov. The immatures of four of these, E. kananaskis, E. occidentalis, E. oresbios, and E. translamellatus, are described.North American Eueremaeus include Eu. acostulatus sp. nov., Eu. aridulus sp. nov., Eu. columbianus (Berlese), Eu. foveolatus (Hammer), Eu. marshalli sp. nov., Eu. masinasin sp. nov., Eu. michaeli sp. nov., Eu. nahani sp. nov., Eu. nemoralis sp. nov., Eu. proximus (Berlese) comb, nov., Eu. woolleyi (Higgins) comb, nov., Eu. yukonensis sp. nov., and three informal species groups with the following included species in North America: (1) Eu. trionus group—Eu. trionus (Higgins) comb, nov., (2) Eu. stiktos group—Eu. carinatus sp. nov., Eu. higginsi sp. nov., Eu. stiktos (Higgins) comb, nov., Eu. tetrosus (Higgins) comb, nov., (3) Eu. chiatous group—Eu. alvordensis sp. nov., Eu. aysineep sp. nov., Eu. chiatous (Higgins) comb, nov., Eu. danos sp. nov., Eu. lindquisti sp. nov., Eu. magniporosus (Wallwork) comb, nov., and Eu. osoyoosensis sp. nov. The immatures of nine of these, Eu. masinasin, Eu. nahani, Eu. carinatus, Eu. higginsi, Eu. columbianus, Eu. proximus, Eu. woolleyi, Eu. stiktos, and Eu. tetrosus, are described. Kartoeremaeus reevesi Higgins and Eremaeus politus Banks are considered junior subjective synonyms of Eueremaeus columbianus (Berlese).A cladistic analysis of the genera comprising Eremaeidae: Eremaeus, Tricheremaeus, Eueremaeus (and included species groups), Proteremaeus, Carinabella, and Asperemaeus, indicates that Eremaeus is the sister taxon of Carinabella, and that Eueremaeus is the sister taxon of Proteremaeus. Tricheremaeus is the sister taxon of Eremaeus + Carinabella, and Asperemaeus is the sister taxon of Eueremaeus + Proteremaeus. The relationship of the Eremaeidae to the Megeremaeidae and Zetorchestidae is presented. Finally, I discuss the ecology and distribution of North American species of Eremaeidae.