The goal of this study was to determine the effect of food supplementation on eastern bluebirds (Sialia sialis) and their nest parasite community across the geographic range of the bluebirds from 2018–2021. We received 674 nests from 69 stewards in 26 states in the eastern United States. Nest box stewards reported whether or not they fed their bluebirds mealworms or suet, then followed the nesting success of the birds (number of eggs laid and hatched, proportion that hatched, number and proportion that fledged). We then identified and quantified parasites in the nests.