They breed in eastern North America and in southern Canada westwards to the Canadian Prairies.

The genus name Setophaga is from Ancient Greek ses, "moth", and phagos, "eating", and the specific pennsylvanicus means "Pennsylvania".

They display dark-streaked gray backs, white faces, black eyestripes and yellow crowns.

Non-breeding birds of both sexes have bright yellow-green crowns, white eye-rings on a grey face, and unstreaked underparts.

[8] They overwinter in Central America to northern Colombia,[10] with a confirmed sighting[11] from as far south as Ecuador.

the chestnut-sided warbler migrates east of the Rocky Mountains, through Bahama, the Greater Antilles and eastern Mexico.

[14] They feed primarily on lepidopteran and dipteran larvae, and will sometimes eat spiders, seeds, and fruits.

[7] They forage actively in shrubs and small trees, and sometimes will attempt to catch insects in mid-air.

Females build the nest into a small cup woven of bark strips, weed stems, grasses, and plant down.

The nest is usually placed in a small crotch of a shrub or vertical tangle of vines no more than 2 m (6.6 ft) above the ground.

The chestnut spots and its class pointed to the individual having a chestnut-sided warbler parent, making it a three-species hybrid.

[17] The extremely rare hybrid was named Burket's warbler after the person who first made the observation of the individual.

The hybrid, located in Pennsylvania, visually looked like a male black-throated blue warbler with brown sides.

However, other species were also suggested to have contributed to creating the hybrids, and no genetic tests were performed to confirm one way or another.

The Breeding Bird Survey BBS in New England has shown an overall decrease in population from 1966 to 2015, but an increase in Pennsylvania.