Red-bellied Woodpeckers (Melanerpes carolinus) feed primarily on arthropods and plant matter, but a growing body of evidence suggests that Red-bellied Woodpeckers may also be a common passerine nest predator. Cerulean Warblers are the fastest declining Neotropical migratory wood warbler in North America. We report our observations of a Red-bellied Woodpecker depredating a nestling Cerulean Warbler (Setophaga cerulea) in Indiana. Further suggesting their status as a recognized nest predator, we also report agonistic behavior of a different Cerulean Warbler pair toward a Red-bellied Woodpecker foraging near the warblers' fledglings. Red-bellied Woodpeckers may be a more common nest predator of Cerulean Warblers than currently recognized, but further research is needed.