The foraminiferal fauna of the Compton, Sedalia and Chouteau Limestones of the Kinderhookian Chouteau Group in Missouri and Illinois described from 83 samples taken at 27 localities, consists of 42 species (including five new, five emended, and one problematic species) belonging to 16 genera and seven families. The fauna of these limestones is essentially identical with fauna of 35 species from the Rockford Limestone of Indiana. About half of the species occur in other Kinderhookian beds from Ohio and Kentucky westward to Oklahoma and Montana. Fourteen Kinderhookian species range downward into the Upper Devonian, and 28, including 11 of the 14, range upward into the Osagean. Seventeen species are restricted to the Kinderhookian, eight occurring widely enough to be regarded as valuable Kinderhookian markers.