Croton has been lectotypified by various authors with two different species, C. aromaticus and C. tiglium. We discuss why C. tiglium has priority. The name for the largest section of Croton has long been accepted to be section Cascarilla, but the recognition of its type species, Croton cascarilla, as a synonym of C. eluteria, the type of section Eluteria, requires a change in the accepted name for the group. The correct basionym and type species of section Geiseleria, which is emerging as one of the three largest New World sections of the genus, is clarified. Lectotypes are designated for C. adenophyllus, C. affinis, C. buchtienii, C. campestris, C. chamaedrifolius, C. fergusonii, C. linearis, C. miquelensis, and C. trinitatis. Epitypes are designated for Clutia cascarilla, Croton chamaedrifolius, and C. linearis.