The Long-tailed Reed-finch (Donacospiza albifrons) is a species of bird traditionally placed in the Emberizidae family. It has been suggested though that it's nearest relations may be the finch-like tanagers of the genus Poospiza in the family Thraupidae. It is the only member of its genus, Donacospiza.

It is found in Argentina, Bolivia, Brazil, Paraguay, and Uruguay. Its natural habitats are temperate grassland, subtropical or tropical seasonally wet or flooded lowland grassland, and swamps.