This account of the archaeology of a cave in southern New Mexico makes a dramatic contribution to the ongoing debate over how long human beings have lived in the Americas. The findings presented here show that human settlement may go back as far as 75,000 years before the present, whereas the long-accepted Clovis dates showed humans only about 12,000 years ago. MacNeish and his colleagues subjected the cave, its environs, and its contents to rigorous interdisciplinary investigation. The first section of this volume comprises their reports on the changing environment of the area. The second section concentrates on the excavation of the cave's layers, presenting the results of radiocarbon dating and describing the evidence of human occupation, including friction skin prints and human hair. The third section discusses the cultural implications of the materials recovered and suggests how the ancient peoples may have exploited the changing environment and developed different ways of life throughout the Americas before the time of Clovis man. No serious discussion of early inhabitants in the New World can disregard the findings presented in this monumental work of scholarship.