ABSTRACTWe investigated the effects of urbanization and resource provisioning on immunity and stress in the American white ibis. We sampled birds captured in the field in Palm Beach County, FL, USA and assessed an individuals physiology based on the habitat they were captured in and the amount of provisioned resources they consumed as determined by stable isotope analysis in a concurrent study. We also raised ibis nestlings in captivity and tested how a simulated anthropogenic diet affects immunity and baseline stress levels. Birds captured from urban habitats had higher bactericidal capacity against E. coli, and adults from urban habitats had an attenuated stress response. Ibises consuming more provisioned resources had better bactericidal capacity against E. coli, lower baseline corticosterone levels in the non-breeding season, and a stronger stress response in the breeding season. A simulated anthropogenic diet had no effect on stress or immunity in white ibis nestlings.