Radiocarbon dates for the terminal Pleistocene are about 2,000 years too young. Furthermore, because of significant carbon perturbations that are manifest as plateaus or abrupt jumps in age, radiocarbon dates of ca. 12,500 to 10,000 B.P. [14C] must be critically evaluated. The first successful human colonization of the Americas occurred not 11,500 but about 13,500 years ago. This basic chronological revision has important implications for models of Paleoindian colonization, population expansion, and genetic and linguistic divergence.