Newly recovered fossils from the Eocene Hoko River Formation of western Washington, USA, constitute the first recognized occurrence of the Cheiragonidae Ortmann in the fossil record. The Cheiragonidae are recognized as a distinct family and are clearly distinguished from the Atelecyclidae Ortmann based on numerous characteristics of the dorsal carapace, appendages, sternum, and chelipeds. The genus Montezumella Rathbun is removed from the Atelecyclidae and placed within the Cheiragonidae. The reassignment of Montezumella to the Cheiragonidae extends the known occurrence of the family into the late Eocene. Montezumella eichhorni n. sp., Trichopeltarion granulosa n. sp. are recognized from Tertiary rocks of Washington, and Trichopeltarion merrinae n. sp. is recognized from late Miocene rocks of New Zealand.