The Rufous-bellied Euphonia is an Amazonian species, which is usually found in pairs and regularly within mixed-species flocks, in the canopy and at borders of humid forest, both on terra firme and in seasonally flooded areas. The species is usually rather uncommon, but it is fairly common locally. It is principally confined to upper and southern Amazonia, and is absent from the Guianan Shield. Males are entirely glossy blue above, and over the throat and upper breast, with rich tawny posterior underparts, with a golden pectoral patch. Females, by contrast, are olive above, with a grayish nape, and becoming slightly more yellowish over the throat, breast, and flanks, with whitish central underparts.