I describe nests and eggs of the White-bellied Seedeater (Sporophila leucoptera) in Brazil. Nests (n  =  5) were cup-shaped and built of thin grass roots and spider web silk with thin walls allowing eggs and young to be seen through them. Nests were in trees (2.5–4.5 m above ground) and close to water. Eggs (n  =  3) were white with black and brown spots concentrated at the large end and measured 19.2 × 13.0 (1.7 g), 18.7 × 13.3 (1.8 g), and 18.8 × 13.9 mm (1.8 g). Both parents fed nestlings, but only females incubated. The White-bellied Seedeater is not presently endangered, but many local populations have been extirpated because of intense commercial trapping and habitat loss. Additional knowledge on the ecology and breeding biology of seedeaters is urgently needed for development of effective conservation plans.