We documented an occurrence of infanticide on a young nestling Florida Grasshopper Sparrow (Ammodramus savannarum floridanus) while conducting a nest camera study on this critically endangered songbird in south-central Florida. The live nestling was removed from the nest by an adult and died on the ground within 5 hrs of eviction. We suspect that this was a case of parental infanticide based on the behaviors of the infanticidal adult, which were consistent with the breeding female at this nest. The adaptive or nonadaptive motivations for the deliberate eviction of a live nestling remain unknown. This is the first report of infanticide in the Grasshopper Sparrow and the genus Ammodramus.