The attractive Cassin’s finch of the montane west is slightly larger and longer winged than the similar purple finch, which it occasionally overlaps with during winter. It is often seen in small flocks, mainly in pine forest, but it is known to occasionally invade into lowland deciduous areas during the winter. It occasionally joins the more common house finch at seed feeders in winter. Polytypic. Length 6.3".

Highly sexually dimorphic with males pink and females brown. Generally lighter pink than other Haemorhous finches, with distinctive fine streaking on the undertail coverts. Male: a bright pinkish-red crown contrasts sharply with a brown streaked nape. The back is heavily streaked and washed pink. The fairly wide eyebrow and submoustachial stripe are both