The Nashville Warbler is closely related to the Orange-crowned Warbler. The two species are similar in size and shape, but have distinct markings. Nashville Warblers have bright yellow undersides extending from their undertail coverts to their throats, and small white patches on their bellies. They have olive-green wings and light gray heads with distinct, white eye-rings. Males and females look similar, but the adult male has a rufous crown that is less distinct in the female. For both sexes, the patch of color is difficult to see in the field.