Twenty-eight species of Euodynerus Dalla Torre are recognized from the Nearctic Region, of which one is Holarctic. Literature on the biology of fourteen species is reviewed and new biological information discussed for four species. The phylogenetic relationships of the genus Euodynerus to other genera and the classification and relationships of the species of Euodynerus are discussed. Seven subgenera are recognized of which four are new: Euodynerus, Pareuodynerus Bluethgen, Leucodynerus Bohart, Annodynerus new subgenus, Gonodynerus n. subgenus, Holodynerus n. subgenus and Plecodynerus n. subgenus. Their comparative morphology, phylogeny, and distrubution are discussed. Larval instars of E. hidalgo (Saussure), E. scutellaris (Saussure), E. notatus (jurine) and mature larva of E. pratensis (Saussure) and E. congresus (Viereck) are compared. Keys, descriptions, illustrations, synonymical names, variation within species and distribution maps are presented. The male of E. megaera (Lepeletier) and the female of E. delicatus (Cresson) and E. digiticornis (Bohart) are newly discribed. The following names are newly synonymized: E. alvarado alvarado (Saussure), E. alvarado afranus (Bohart), E. annulatus avensis (Saussure), E. annulatus evectus (Cresson), E. annulatus imperialis (Bohart) and E. annulatus sulphureus (Saussure) = E. annulatus (Say), E. provisoris (Viereck), E. tempiferus tempiferus (Viereck), E. tempiferus birepandus (Bohart), E. tempiferus eldoradensis (Rohwer), E. tempiferus pritchardi (Bequaert), and E. tempiferus subrueus (Bohart) = E. annectens (Saussure), E. auranus albivestis (Bohart), E. auranus equilus (Bohart) and E. auranus azotopus (Bohart) = E. auranus (Cameron), E. barberi (Bohart) = E. cluniculus (Saussure), E. boscii boharti (Krombein), E. b. molestus (Saussure) and E. guerrero (Saussure) = E. boscii (Lepeletier), E. castigatus rubrivestis (Bohart) and E. c. sanneovestis (Bohart) = E. castigatus, E. crypticus (Say), and E. crypticus stricklandi (Bequaert) = E. crypticus (Say), Odynerus orasus Camerson = E. delicatus (Cresson), E. exoglyphys albovittatus (Bohart) = E. exoglyphus (Bohart), E. schwarzi (Krombein) = E. foraminatus (Saussure), E. foraminatus aequalis (Cameron), O. santafeae (Cameron) and E. foraminatus blakeanus (Cameron) = E. scutellaris (Saussure), E. leucomelas leucomelas (Saussure), and E. l. oregonensis (Bohart), E. foraminatus apopkensis (Robertson) and E. f. parvirudis (Bohart) = E. notatus (Jurine), E. hidalgo viereckii (Cameron) and E. hidalgo boreoorientalis (Bequaert) = E. hidalgo (Saussure), E. pratensis brumalis (Bequaert) = E. pratensis (Saussure). E. foraminatus scutellaris is raised from subspecies to species status.