The Barleeidae, a family of minute, marine rissoacean gastropods, is diagnosed and distinguished from the Rissoidae, with which it has usually been associated and with which it is convergent, particularly in shell form. Two subfamilies are recognized, the Barleeinae, containing five genera, two of which are new, and the Anabathrinae, containing 8 genera, one of which is new. The anatomy of several species in both subfamilies is described and the evolution of the female genitalia, in particular, is discussed. The shells, radulae, opercula and, where known, features of the head-foot and anatomy are described for each genus and typical species listed. The Barleeinae is centred in the warm-temperate and tropical eastern Pacific and the Anabathrinae in Australasia. The relationship of the Barleeidae to other families in the lower mesogastropods is briefly discussed.