Reuse of ephemeral open cup nests by passerines is an uncommon behavior. We report the first case of nest reuse by federally endangered black-capped vireos (Vireo atricapilla). The initial use of the nest was unsuccessful because the clutch was parasitized by a brown-headed cowbird (Molothrus ater) during egg laying and then depredated during incubation. During reuse, apparently by the same pair of vireos, the nest escaped parasitism but was depredated when the nestlings were 7 d old. Although rare, this behavior may be an example of phenotypic plasticity in black-capped vireo nesting strategies. Despite failure in this instance, nest reuse may be adaptive if it reduces the risk of brood parasitism but could be maladaptive if it increases the risk of nest predation.