The Yellow Warbler, Dendroica petechia, is a New World warbler. It is the most widespread Dendroica warbler, breeding in almost the whole of North America and down to northern South America.

The Yellow Warbler proper (aestiva group) breeds in the whole of North America as far south as central Mexico in open, often wet, woodland or shrub. It is migratory, wintering in Central and South America. This form is a very rare vagrant to western Europe. It is 11.5 cm long and weighs 9 g. The summer males of this group are greenish above and yellow below, with red breast streaking. The various aestiva group races vary mainly in brightness.

These birds feed on insects and spiders, but northern races will also take some berries, namely in their winter quarters.

Yellow Warblers nest in trees, building a cup nest. Birds of the aestiva group lay 3-6 eggs, but the two other groups, which breed in mangroves, lay fewer eggs, as would be expected for tropical races.

Other plumages of all races are essentially greenish above and a duller yellow below, although young males soon acquire breast and, where appropriate, head colouration.

The song is a musical sweet sweet sweet, I'm so sweet, although it varies considerably between races. The call is a soft or harder ship.

The Yellow Warbler is a regular host of the Brown-headed Cowbird, a nest parasite, and it has evolved strategies to combat such nest parasitism. Upon discovering a cowbird egg laid in its nest, the warbler will often build a new layer to the nest, covering up the cowbird egg (and its own eggs, if they have been laid). In other circumstances, the bird may desert the nest altogether.