There is very little information on the breeding biology of Volcano Junco. The breeding season is March to July (Stiles and Skutch 1989). The nest is placed on the ground, under a rock, log, or bush, or in a niche on a mossy bank (Wetmore et al. 1984, Stiles and Skutch 1989). The nest is a cup, composed of grass stems but lined with animal hair and thistle floss; sometimes the outside of the cup also is decorated with moss (Wetmore et al. 1984, Stiles and Skutch 1989). The clutch is two; the eggs are pale blue, with a few brown or lilac dots, concentrated around the large end (Wetmore et al. 1984, Stiles and Skutch 1989). The dimensions of the eggs of one clutch were 22.06 x 16.33 mm and 23.12 x 16.81 mm (Wetmore et al. 1984). There is no information on the length of incubation or of nestling development, or on parental care.