The fawn-breasted tanager has an average body length of 14 cm (5.5 in) and can weigh 18–25 g (0.63–0.88 oz). This species of tanager has an unusually short, wide beak, similar to the beaks of swallows, as well as short legs and tail, and long wings. The most noticeable coloration of this species is its sky-blue crown and broad black mask that extends over the eyes into ear-coverts. The coloration of male crown and nape is a medium blue, and the forehead, lores, ocular area and ear-coverts are deep black. The mantle and back of males are a dull blue color, the lower back and rump a bright turquoise-blue, tail dusky blue, throat and the underparts of the body are a cinnamon color. The iris is a dark red to reddish-brown color, and the bill is dusky with a lower mandible that is normally grey. The female has a similar coloration but is usually duller, particularly in the crown region, and with a brownish coloration on the back. Juveniles are almost without pattern and have a dull brownish-grey coloring. The fawn-breasted tanager is usually seen singly or in pairs, most often in the semi-open, but it may perch at any height.
Calls consist of "see" or "swee" tones varying in sets of 4 or 5 notes sung slowly, or a higher number of notes, around a dozen, uttered in a pulsating trill pattern in a faster rhythm.
The range of the fawn-breasted tanager extends throughout South America, covering most of Brazil, Venezuela, Colombia, Peru, Ecuador, Bolivia, east Paraguay, Uruguay, Northeastern Argentina, following towards the southern bank of the Río de la Plata. The species can be found in habitats along forest borders, bushy pastures, and cultivated small semi open areas with large trees and clearings with scattered trees. The elevation range that this species can tolerate varies geographically. In the Andes and Ecuador it can be found at altitudes of 1500–2500 m, with a maximum of 3000 m. In Colombia, it occurs down to 900 m, and in Venezuela to 400 m.
The species has a mixed diet which includes vegetable matter such as berries, fruit pulp, buds, flowers and seeds, as well as insects such as moths, butterflies or larvae. It may form part of mixed species flocks and has been known to congregate at fruiting trees with other birds, but generally feeds alone.
The species is currently classified as Least Concern by the IUCN due to its extremely large range, variety of habitats and apparently large population size. Due to opening of forested areas through agriculture and other anthropogenic changes, it may be expanding its range locally.
