The first formal description of the black-faced grassquit was by the Swedish naturalist Carl Linnaeus in 1766 in the twelfth edition of his Systema Naturae.

[6][7] Eight subspecies are recognised:[7] A male black-faced grassquit is around 10 cm (3.9 in) long and weighs approximately 10 g (0.35 oz).

Females and immature birds have dull olive-grey upperparts and head, and paler grey underparts becoming whiter on the belly.

[citation needed] The male has a display flight in which he flies for short distances, vibrating his wings and giving a buzzing dik-zeezeezee call.

[8] This is a common bird in long grass or scrub in open or semi-open areas, including roadsides and ricefields.