The female is olive-green above and yellow-olive below, with a grayer patch running down the center of her breast and abdomen, and bright yellow undertail coverts.

It is primarily a fruit-eater, specializing on mistletoe berries, but also eating other fruits, as well as occasional seeds and invertebrates.

Both parents build a globular nest of dried grass and stems, lined with finer material and with a side entrance.

Across its range, it is considered a species of least concern, though it is rare on Trinidad due to overtrapping for the caged bird trade.

[6][7] Its range is largely distinct, or allopatric, from that of the latter species, overlapping only in a narrow zone in eastern Venezuela.

[9] When Anselme Gaëtan Desmarest created the genus Euphonia in 1806, he assigned it to the tanager family Thraupidae.

There it remained for nearly 200 years, until molecular DNA studies done in the late 20th and early 21st century revealed that euphonias were more closely related to the finches than the tanagers.

[12] The Trinidad euphonia is a small, stout, short-tailed passerine, measuring 9.7–11 cm (3.8–4.3 in) in length[nb 1] and weighing 8.8–14 g (0.31–0.49 oz).

[15] The female is olive-green above and yellow-olive below, with a grayer patch running down the center of her breast and abdomen, and bright yellow undertail coverts.

A "notably vocal" species, the Trinidad euphonia has whistled calls that are high-pitched, plaintive, and hard to locate.

[7] One regular call, variously transcribed as "pee", "tee", or "dee", is typically doubled, though sometimes it is repeated 3–5 times, and exceptionally up to 20.

[6][14][15] Another regular call, transcribed as "duu dee", "puwee", or "cooleee", is sung rapidly on two pitches, with the second note higher.

[6][15] The male orange-bellied euphonia has a rufous rather than yellow forehead, and darker underparts, while the female sports a grayish nape.

Male purple-throated euphonias tend to be glossed with a purplish rather than bluish sheen; their yellow crown extends to just behind their eyes.

[17] This may be an adaptation to deal with mistletoe berries, as this stomach modification is shared with other Euphonia species that have similarly specialized diets.

[4][9] The International Union for Conservation of Nature rates the Trinidad euphonia as being a species of least concern, due to its very large range and apparently stable population.

[1] However, it is rare and local on Trinidad, where trapping for the caged bird trade has greatly reduced its numbers.