A medium-sized sparrow at 14–16 centimetres (5.5–6.3 in), it has distinctive plumage, including large pale head stripes in both sexes.

Its plumage is mostly grey, brown, and chestnut, and the male has some bold black and white markings on its head and neck.

The species inhabits semi-arid savannah, cultivated areas, and towns, and ranges from the central coast of Angola to eastern South Africa and Eswatini.

The Cape sparrow's population has not been recorded decreasing significantly, and it is not seriously threatened by human activities, so it is assessed as a species of least concern by the International Union for Conservation of Nature (IUCN).

[4] The breeding male has a mostly black head, but with a broad white mark on each side, curling from behind the eye to the throat.

Within this genus, morphological comparisons and geography were insufficient to elucidate to which species the Cape sparrow is most closely related.

[9] The Cape sparrow's specific epithet comes from the Greek μέλας (melas, "black") and ουρά (oura, "tail"),[10] while the name of the genus Passer comes from a Latin word for small birds.

[3] The eastern limit of its range is reached in the wet forests of Limpopo and KwaZulu Natal, extending into the hills of western Eswatini.

[13] The original habitats of this species were the semi-arid savanna, thornveld, and light woodland typical of southern Africa.

[14] The Cape sparrow prefers habitats with an annual rainfall of less than 75 centimetres (30 in), though in desert areas it is usually found near watercourses or watering holes.

While it occurs in urban centres, it prefers parks, gardens, and other open spaces, and has a low reproductive success in more built-up areas.

Birds from urban areas form large flocks seasonally and fly out to the nearby countryside to feed on ripening grain, returning at night to roost.

[17] The larger seeds of cereals, wild grasses, and other small plants are preferred, with wheat and khakiweed (Alternanthera caracasana) being favourites.

The Cape sparrow eats the soft shoots of plants, and probes in aloes for nectar, but these are not important sources of food.

Once ready to breed, newly mated pairs look for a suitable nesting site, spending mornings searching, and returning to their flock in the afternoon.

Ornithologist J. Denis Summers-Smith observed a display in which the male hopped beside the female in a tree, drooping its wings and ruffling the chestnut-coloured feathers on its back.

In the house sparrow a similar display exists, in which a female who is not ready to copulate is chased by her mate, who is joined by other males.

In cavity nests, the hole is filled with a shapeless mass of grass with a cup of soft material containing the eggs on the inside.

[20] The inside linings of Cape sparrow nests can incorporate large portions of aromatic leaves such as wolbossie (Helichrysum pumilio), thyme (Thymus vulgaris), and camphor (Cinnamomum).

Presumably owing to the greater availability of food, clutches are larger during the peak of the breeding season, and in more southern latitudes of the Cape sparrow's range.

[22] Cape sparrows are among the main hosts of brood parasitism by the dideric cuckoo in southern Africa,[13] and sometimes parasitise nests of their own species.

[26] The Cape sparrow is an abundant and familiar bird of human habitations and cultivation in most of southern Africa.

[4][14] The Cape sparrow was featured on the lowest-denomination South African coin, from the farthing (¼-cent) in 1923 to the cent that ceased to be minted in 2002, with designs based on an original by George Kruger Gray.

This was said to be because women interned at a concentration camp in Bethulie during the Boer War adopted a biblical quotation (from Matthew 10) as their motto: "Are not two sparrows sold for a farthing?