The purpose of this study is to call attention to the widespread occurrence of early Mississippian arenaceous Foraminifera in the United States and to classify the faunas for subsequent systematic detailed studies. They are represented in Lower Mississippian rocks from the Welden Limestone of Oklahoma, Chappel Limestone of central Texas, and Lodgepole Limestone of southwestern Montana, and they are compared with a similar described fauna from the Rockford Limestone of northern Indiana. Eleven genera and 33 species, 12 of which are new, are identified from among the families Astrorhizidae, Saccamminidae, Hyperamminidae, Reophacidae, Tolypamminidae, and Lituolidae. A summary is given of species in early Mississippian strata in the United States which total 16 genera and 49 species. The Welden, Chappel, and Rockford faunas are considered to have been deposited in cool shallow aerated waters which were affected by wave and current energies just strong enough to produce turbidity. The Lodgepole Limestone in southwestern Montana was deposited in deeper less aerated waters at the edge of the open marine shelf (basin edge) corresponding to Rich's clinoform depositional environment. While arenaceous Foraminifera are common, caleareous forms have not been recognized in these rocks.