Northern Chile’s Atacama Desert is one of the most unforgiving landscapes on the planet; however, a variety of complex risk-mitigation strategies facilitated long-term human occupation of the region. Using a burgeoning corpus of human, floral, and faunal stable carbon and nitrogen isotope data, the present work examines patterns of mobility, exchange, and social interaction in northern Chile’s Formative Period (1500 BC–AD 400). While the geographic barriers and harsh climatic conditions of the Atacama Desert, in concert with substantial logistic considerations, established constraints on human diet at the site and local levels, regional dietary variation speaks to frequent and possibly even regular interzonalmovements of people and/or foodstuffs. Through isotopic analysis of the remains of 86 individuals, we examine regional patterns of dietary variation in light of recently advanced hypotheses concerning the nature of mobility, exchange, and social interaction in Formative Period northern Chile. These data indicate both systematic regional exchange in foods and other goods and the central role of sites in the Calama oases in facilitating this exchange and movement.