Ornithologists originally classified euphonias and chlorophonias with tanagers in the family Thraupidae before molecular work in the late 1990s showed that they are actually finches and belong in Fringillidae alongside siskins, goldfinches, and their allies.

Euphonia luteicapilla is a very small bird, ranging in length from 86-96 mm. The male's entire crown and most of his undersurface are bright yellow. The throat and rest of its upper parts are steel blue. Females are a yellowish olive color on their upper surface and have an underside of dull yellow.

Euphonia violacea The ball nest is built on a bank, tree stump or cavity and the normal clutch is four, sometimes three, red-blotched white eggs, which are incubated by the female. Adult violaceous euphonias are 11.4 cm long and weigh 14 g.