Corinnidae is a family of araneomorph spiders, sometimes called corinnid sac spiders. The family, like other "clubionoid" families, has a confusing taxonomic history. Once it was a part of the large catch-all taxon Clubionidae, now very much smaller. The original members of the family are apparently similar only in that they have eight eyes arranged in two rows, conical anterior spinnerets that touch and are generally wandering predators that build silken retreats, or sacs, usually on plant terminals, between leaves, under bark or under rocks.
Two former subfamilies of the Corinnidae are now treated as separate families, Phrurolithidae and Trachelidae. As now recognized, Corinnidae contains 67 genera and over 720 species worldwide. Among the common genera are Castianeira (nearly world wide) and Corinna (widespread).
Members of the genus Castianeira appear to be mimics of ants and velvet ants. Other corinnid ant-like genera include Mazax, Myrmecium and Myrmecotypus. Corinna is the type genus for the family and consists of small running spiders.