Reviews the palaeoenvironmental context for Palaeoindian and Early Archaic settlement of the south-central Andes. In an attempt to reconcile proposals for late-glacial and early Holocene environmental changes that have originated in several Quaternary sciences. Most useful are the records of changing lake levels, geomorphological indicators of glacial advance and retreat, changes in vegetation as seen through pollen stratigraphy, the record of large mammal extinctions, and the archaeological settlement pattern itself. High lake stands in the central and south-central Andes, c. 12,500 to 11, 000 BP, seem to correspond to glacial retreat. Palynological studies also suggest higher temperatures, coincident with greater summer precipitation from 11,500 BP to perhaps 10,000 BP, followed by some reduction in temperatures and then widespread aridity from about 8500 to 5000 BP. Environmental change at the Pleistocene/Holocene boundary was at least a major contributing factor to the extinction of horse and sloth around 10,000 BP. Archaeology of the salt puna and Punta Negra region conforms well with the environmental record, showing human entry by the Early Archaic (11,000-8000 BP), subsequent depopulation and perhaps abandonment, then readaptation to more localized resources in the Late Archaic (5500-4000 BP).