 Prevost's ground sparrow is on average 15 cm long and weighs 28 g. The adult has a stubby dark-grey bill, unstreaked olive-brown upperparts, a rufous crown and mainly white underparts.Young birds are browner above, have yellower underparts, and a duller indistinct head pattern.It has a simple head pattern in which the rufous of the crown extends down the sides of the neck as a half collar behind the white face.