Adult females have light brown upperparts and light underparts with brown streaks throughout; their facial markings are less distinct than those of the female purple finch.

Their breeding habitat is coniferous forest in mountains of western North America as far south as northern New Mexico and Arizona; also Southern California near Baja California.

Some non-breeding birds winter as far south as central interior Mexico.

These birds forage in trees, sometimes in ground vegetation.

This bird was named after John Cassin, who was a curator at the Philadelphia Academy of Natural Sciences.