Timing of breeing varies from region to region, with dates in Ecuador including June, July, August, and September (Sheldon and Greeney 2007).
Nest: The following description is based on a nest described by Sheldon and Greeney (2007) in Ecuador. The nest of the Beryl-spangled Tanager is in the shape of an open cup, measuring 10.5 cm wide to about 6.5 cm tall (outside dimensions). The inner egg cup measures about 5 x 5 cm. The nest is fairly neat, with a neat mossy cup in the inside that also included a few small fern leaves and rootlets, which are used to bind it together. The inner lining was circular and about 0.7 cm thick, it was mostly composed of dead, pale Chusquea scandens (Poaceae) leaves and intersected with a few dark rootlets. The nest was about 6.5 m above the ground, saddling over the center of a 45° y-shaped split on a branch (Sheldon and Greeney 2007). It was located on the outer edge of surrounding vegetation, roughly about 15 m below the canopy crown (Sheldon and Greeney 2007).
Eggs: Eggs of the Beryl-spangled Tanager are a creamy white or pale green color (Isler and Isler 1999). They are thickly marked with brown and lilac hues, especially towards the large end of the egg (Isler and Isler 1999).
Clutch size: Sheldon and Greeney (2007) observed two nestlings.
Brooding of nestlings: Sheldon and Greeney (2007) were uncertain if both parents brooded the nestlings, but the adults leave the young unattended for up to a day. The percentage of brooding during daylight hours ranged from 0.6 to 6%, and brooding bouts were generally short (average 1.9 minutes). However, each evening, an adult returned to the nest and apparently brooded throughout the night. Adults tend to brood facing the same direction (Sheldon and Greeney 2007).
Parental care: The nestlings were seen being fed by both adult parents (Sheldon and Greeney 2007). However, unlike other observations of some other species of Tangara, there were no helpers present (Sheldon and Greeney 2007). Parents fed their nestlings an average of 7.2 feeds per nestling-hour (Sheldon and Greeney 2007). However, later in the day, these feedings tend to decrease. The highest feeding rates occur at 6-7:00 hr at 11.6 feeds per nestling-hour, while the lowest feeding rates occur at 16-18:00 hr, with an average rate of about 4.15-4.25 feeds per nestling-hour (Sheldon and Greeney 2007). Also, the latest feeding time occurs no later than 18:17hr. Parents were observed feeding their nestlings Miconia berries (Sheldon and Greeney 2007).
Fecal sacs that were not ejected by the nestlings usually were carried away, and sometimes were consumed, by the adults (Sheldon and Greeney 2007).