The Lesser Goldfinch or Dark-backed Goldfinch (Carduelis psaltria) is a very small songbird of the Americas. Together with its relatives the American Goldfinch and Lawrence's Goldfinch, it forms the American goldfinches clade in the genus Carduelis sensu stricto.

The American goldfinches can be distinguished by the males having a black forehead, whereas the latter is (like the rest of the face) red or yellow in the European Goldfinch and its relatives.

At 4-4.5 inches (10-11 cm) long and about 0.3 oz (9.5 g) in weight, it is the smallest North American Carduelis species. Males are easily recognized by their bright yellow underparts and big white patches in the tail (outer rectrices) and on the wings (the base of the primaries). Males in most of the range have solid black upperparts, but those of the subspecies hesperophilus, in the far western U.S. and northwestern Mexico, have olive-green napes and backs. Both green-backed and black-backed (Arkansas Goldfinch, nominate subspecies psaltria) males occur in Colorado and New Mexico, as do intergrades, and only black-backed males occur in southwestern Texas and most of Mexico. Males of the subspecies colombianus, east and south of the Isthmus of Tehuantepec, are richer yellow below.

Females' and immatures' upperparts are more or less grayish olive-green; their underparts are yellowish, buffier in immatures. They have only a narrow strip of white on the wings (with other white markings in some forms) and little or no white on the tail. They are best distinguished from other members of the genus by the combination of small size, upperparts without white or yellow, and dark gray bill. In all plumages this bird can easily be taken for a New World warbler if the typical finch bill isn't seen well.

Like other goldfinches, it has an undulating flight in which it frequently gives a call: in this case, a harsh chig chig chig [Sibley]. Another distinctive call is a very high-pitched, drawn-out whistle, often rising from one level pitch to another (teeeyeee) or falling (teeeyooo). The song is a prolonged warble or twitter, more phrased that that of the American Goldfinch [Peterson], often incorporating imitations of other species.

This American goldfinch ranges from the southwestern United States (near the coast, as far north as extreme southwestern Washington) to Venezuela and Peru. It migrates from the colder parts of its U.S. range.

The Lesser Goldfinch often occurs in flocks or at least loose associations. It utilizes almost any habitat with trees or shrubs except for dense forest, and is common and conspicuous in many areas, often coming near houses. It is common at feeders in the Southwest United States and will come almost anywhere with thistle sock feeders. Flocks of at least six birds will often be seen at feeders. It feeds mostly on tree buds and weed seeds; geophagy has been observed in this species.

The nesting season is in summer in the temperate parts of its range; in the tropics it apparently breeds all-year round, perhaps less often in September/October. It lays three or four bluish white eggs in a cup nest made of fine plant materials such as lichens, rootlets, and strips of bark, placed in a bush or at low or middle levels in a tree.

Considered a Species of Least Concern by the IUCN due to its vast range, it nonetheless seems to be declining locally. For example, it is rare in the Ecuadorean Andes foothills.