At about 4.75 inches (12 cm) long and weighing about 0.4 oz (11.5 g), it is slightly bigger than the Lesser Goldfinch and slightly smaller than the American Goldfinch, with less yellow in the plumage than either. Adults of both sexes are gray with pink to grayish flesh-color bills, stubbier than other goldfinches'. They have yellow rumps and paired yellowish wing-bars, as well as yellow edges on the flight feathers and yellow on the breast. The tail is black, crossed by a white band (Sibley 2000, Oiseaux.net 1996–2007). Plumage is duller in winter, brightening after a spring molt (Davis 2001, Oiseaux.net 1996–2007). Males are paler, with black caps and faces and larger areas of brighter yellow. Females are browner, have less and duller yellow, and lack the black (Sibley 2000, Oiseaux.net 1996–2007). Juveniles resemble females but are even duller and have faint streaks on the upperparts and especially the underparts. (Davis 2001, Oiseaux.net 1996–2007).
Calls include "a nasal too-err, also a sharp, high PIti and Itititi" (Sibley 2000). The flight call, which is diagnostic, is given as "a high, clear ti-too" (Sibley 2000) or tink-ul "reminiscent of glass wind-chimes" (Davis 2001). The song is high-pitched, continuous, and limited in frequency range, including wind-chime notes and especially imitations of other species' calls and other simple and distinctive sounds (Sibley 2000, Davis 2001). Males sing in winter but mostly in the breeding season. Females sing occasionally and briefly (Davis 2001).