Sushkin (1927) concluded that the waxbills were most closely related to the whydahs (Vidua), but belonged as a subfamily in the Ploceidae. Tordoff (1954) on the basis of skull characters placed the Estrildinae in the Ploceidae, near the Carduelinae.
In addition, 23 skeletons of eight species of Viduinae and 52 skeletons of 22 species of 13 genera of Ploceidae (two genera of Bubalornithinae, five of Passerinae, and six of Ploceinae) were compared.