The Emberizidae family probably originated in South America and spread first into North America before crossing into eastern Asia and continuing to move west. This explains the comparative paucity of emberizid species in Europe and Africa when compared to the Americas.
In North America, most of the species in this family are known as (American) Sparrows, but these birds are not closely related to the Old World sparrows which are in the family Passeridae. The family also includes the North American birds known as juncos and towhees.
As with several other passerine families the taxonomic treatment of this family's members is currently in a state of flux. Many genera in South and Central America are in fact more closely related to several different tanager clades, and at least one tanager genus (Chlorospingus) may belong here in the Emberizidae.
Emberizids are small birds, typically around 15 cm in length, with finch-like bills and nine primary feathers. The family ranges in size from the Sporophila seedeaters, the smaller species of which are about 10 cm and weigh 9-10 grams, to the Abert's Towhee, at 24 cm (9.5 in), and the shorter-tailed, but chunkier Canyon Towhee, at 54 grams (1.9 oz). They live in a variety of habitats, including woodland, brush, marsh, and grassland. The Old World species tend to have brown, streaked, plumage, although some New World species can be very brightly coloured. Many species have distinctive head patterns. Their diet consists mainly of seeds, but may be supplemented with insects, especially when feeding the young.
The habits of emberizids are similar to those of finches, with which they sometimes used to be grouped. Older sources may place some emberizids in the Fringillidae, and the common names of some emberizids still refer to them as finches. With a few exceptions, emberizids build cup-shaped nests from grasses and other plant fibres, and are monogamous.
The relationships of these birds with other groups within the huge nine-primaried oscine assemblage are at this point largely unresolved. Indeed relationships within the Emberizidae as defined here are uncertain with the possibility that each of the three main groups may not be all that closely related.