Recent excavations at the site of Soro Mik’aya Patjxa in the south-central Andes have revealed the earliest securely dated cultural features in the Lake Titicaca Basin. Radiocarbon assays show that the site was occupied across the Middle to Late Archaic period transition between 8000 and 6700 cal BP. The rich material assemblage makes it possible to identify behavioural patterns among these last hunter-gatherers of the Titicaca Basin, which anticipate later developments in the trajectory to socioeconomic complexity. Mobile hunter-gatherers appear to have occupied the site repeatedly for more than a millennium. Evidence for intensive subsistence practices and interpersonal violence foreshadow the emergence of incipient sedentism, food production and land tenure in subsequent periods.