The analysis of more than 1,300 flotation samples from thousands of excavated cultural features dating to the San Pedro phase (1220–730 BC) at the Las Capas site in southern Arizona provides evidence of long-term continuity and change in plant cultivation and collection practices in response to environmental disturbances during the Late Archaic period (2100 BC–AD 50). Although preceramic foodways in the region are widely considered to have been stable for roughly 2,500 years following the introduction of maize prior to 2100 BC, analyses of macrobotanical data reveal that moderate-intensity flood events during the Middle San Pedro phase (930–800 BC) preceded the greatest richness and diversity of harvested plants, while reliance on maize was reduced. In contrast, in periods with little environmental disturbance maize was more dominant, with less diversity in other cultivated and foraged plants. Novel cultivation, processing, and foraging practices were initiated in response to disturbance but persisted after floodplain conditions stabilized. It is argued that the reciprocal relationship between disturbance and botanical diversity is integral for understanding the long-term resilience of Late Archaic foodways and that this relationship is best modeled using ecological theories termed the Intermediate Disturbance Hypothesis and the Intermediate Productivity Hypothesis.