Over a century ago Herrich-Schaeffer in his Nomenclator Entomologicus illustrated and characterized an unnamed genus of small wasps. Subsequently in 1869, Giraud figured and fully described it under the name Ammoplanus. Until recently, however, the genus has received little attention, probably because of the extremely small size of the component forms and their relative rarity in collections. Several years ago Dr. P. H. Timberlake of Riverside, California, kindly forwarded to me for study a remarkable collection of Ammoplanus and related genera taken by him in southern California. All of these, except Ammoplanus, have been reported upon elsewhere. The present paper is a review of the Nearctic species of Ammoplanus, based largely upon the southern California material collected by Dr. Timberlake.