Three subfamilies are classified in Eupelmidae: Calosotinae Bouček, Eupelminae Walker, and Metapelmatinae Bouček. Diagnoses of these three subfamilies and of Tanaostigmatidae are given, together with a key to distinguish members from each other and from other Chalcidoidea. Genera of Calosotinae and Metapelmatinae are revised for the world, with a key to genera given for both subfamilies. For each genus the following is provided: synonymy, description of structural features of males and females, notes on distribution and hosts, available keys to species listed by biogeographic region, and a catalog of species. New generic combinations are made in the catalogs of species based on examination of type specimens of the species. Eight genera are included in Calosotinae [type species in brackets]: Archaeopelma gen.nov. [A. tropeotergum sp.nov.], Licrooides gen.nov. [L. umbilicatus sp.nov.], Paraeusandalum gen.nov. [P. chilense sp.nov.], Eusandalum Ratzeburg, Chirolophus Haliday, Calosota Curtis, Balcha Walker, and Tanythorax gen.nov. [T. spinosus sp.nov.]. Four genera are included in Metapelmatinae: Metapelma Westwood, Neanastatus Girault, Eopelma gen.nov. [E. mystax sp.nov.], and Lambdobregma gen.nov. [L. schwarzii (Ashmead) comb.nov.]. The following are proposed as new synonymies: Notosandalum De Santis and Exosandalum Bouček = Eusandalum Ratzeburg, and Metacalosoter Masi = Calosota Curtis. Eighteen structural features of adults of the three eupelmid subfamilies, and of other Chalcidoidea including Tanaostigmatidae, Encyrtidae, Aphelinidae, and Pteromalidae, are studied to delimit character states and determine their distribution among the higher taxa. Twenty-two additional features of adults of Calosotinae and Metapelmatinae are studied for supplemental evidence of relationships among the genera in these two subfamilies. Observed character-state distributions are used to postulate character polarity and homoplastic states, and hypotheses of monophyly and relationships among taxa are based on proposed synapomorphic states. Aphelinidae sensu lato (including the subfamily Eriaporinae) are indicated as either a paraphyletic or polyphyletic taxon if the Eriaporinae are included but the Signiphoridae are excluded. Tanaostigmatidae sensu lato (including the genus Cynipencyrtus Ishii) are indicated as the sister group of Encyrtidae based on a relatively long mesoscutal process for the muscle pl2–t2c, and structure of the articulation between the mesoscutum and scutellar-axillar complex. The genus Cynipencyrtus Ishii is indicated to be most closely related to Encyrtidae based on common possession of transverse axillae and mesotibial apical pegs. Possible relationships among Calosotinae, Metapelmatinae, and Eupelminae, and among these and Tanaostigmatidae + Encyrtidae remain unresolved. There are no derived character states unique to either Eupelmidae, or Eupelmidae + (Tanaostigmatidae + Encyrtidae), so that these taxa and relationships are not definitively supported as monophyletic. Eupelmidae may represent a grade-level taxon with membership determined by similar suites of apomorphic states that function to enhance jumping ability. Cladograms are used to illustrate alternate hypotheses of character-state evolution and relationships among the genera of Calosotinae and Metapelmatinae. Distribution of character states for the higher taxa and for each genus of Calosotinae and Metapelmatinae is summarized in two tables. Scanning electron photomicrographs are used to illustrate structural features.