It is a slim, long-tailed bird, primarily gray with a reddish-brown back streaked with black, brown wings and tail, a pink beak, and brownish legs and feet.

An unobtrusive bird, it spends much of its time foraging slowly along the ground, either alone or in small groups, sometimes mixing with other Spizella species.

It builds a cup-shaped nest of grasses, rootlets, or plant fibers, into which the female lays 2–5 pale blue eggs.

German ornithologist Jean Louis Cabanis first described the black-chinned sparrow in 1851, using a specimen which is thought to have been collected near Mexico City.

[7][8] There are four recognized subspecies: The genus name Spizella is a diminutive of the Ancient Greek word spiza, meaning "finch".

[16] Overall, it is a slender, round-headed bird, with a high crown and a long, notched tail, which is proportionately longer than that of other Spizella sparrows.

[15] In alternate plumage (during the breeding season), the male has extensive black on its chin, throat and the front of its face.

[5][14] Recent fledglings may have darker bills, as well as notably short tails, yellow gapes, and paler gray heads.

[14] The song is a series of clear, high-pitched whistles that accelerate into a rapid trill, which typically rises in pitch.

[14] Though similar in plumage to the dark-eyed junco, the black-chinned sparrow is slimmer, and has a streaked back, brown edges to its wing feathers, and no white in its tail.

It is regularly found from northern California east to western Texas, and as far north as southern Nevada and Utah,[20] and has occurred as a vagrant or occasional breeder in Oregon and Colorado.

[21][22] A species of arid and semi-arid places, it lives in chaparral, sagebrush, pine-juniper woodlands, and other brushy shrubland.

[15] In the United States, it is sometimes found in small, loose groups, occasionally mingling with Brewer's or chipping sparrows.

[3][5] Though the species often remains in deep cover, breeding males defy that more typical behavior and pick conspicuous, exposed perches from which to sing.

[31] Though its diet is not well-known, it appears to feed primarily on seeds as a ground-gleaning granivore in the winter, and on insects as a ground-foraging omnivore in the summer.

[33] It appears to obtain all of the moisture it needs from its food during the summer, but in the winter may travel a considerable distance to reach a water source.

[36] The nest is a shallow, open cup built of plant material, including grasses, weed stems, rootlets, or yucca fibers.

[24] Both parents provide food for the nestlings and remove fecal sacs for the 11–13 days it takes for the young to fledge.

[38] Other suspected nest predators include western scrub jays, snakes, lizards, rodents, and ants.

[23] On the other hand, the International Union for Conservation of Nature considers it to be a species of least concern, due to its substantial population and very large range.