Illustrated key to genera and catalogue of Mymaridae (Hymenoptera) in America north of Mexico.

Identification keys for females, and for males where known, to the 39 genera and 11 subgenera of Mymaridae in America north of Mexico are given. The genera are illustrated with over 1010 photographs and/or scanning electron micrographs. The 202 currently named and valid species reported from America north of Mexico are catalogued. Reliable host records are reported for 16 genera and almost 90 species from rearings in the region. The five genera represented by more than one subgenus in the region are: Anagrus Haliday, Anaphes Haliday, Erythmelus Enock, Kalopolynema Ogloblin, and Polynema Haliday. Five other genera are represented only by unnamed and possibly undescribed species. About 1000 literature references, mainly the North American ones, are listed. Three new species are described: Callodicopus floridanus Huber, sp. n., Neostethynium americanum Huber, sp. n., and Stephanocampta xanthogaster Huber, sp. n. Cosmocomoidea marilandica (Girault), stat. rev., is placed in synonymy under C. dolichocerus (Ashmead). Platypatasson Ogloblin is given subgeneric status as Platystethynium (Platypatasson Ogloblin), stat. rev. Corrections and additions to the mymarid fauna of Mexico by Guzmán-Larralde et al. (2017) are also given.