Until recently, the Cebus-Saimiri clade was placed within the large-bodied Cebidae, which included the howler monkeys, spider monkeys, muriquis, titi monkeys, uakaris, and sakis. New phylogenetic analyses ally Cebus-Saimiri with the owl monkeys, Aotus, as the sister group to the Callitrichidae, the marmosets and tamarins. This revision of the Platyrrhini taxonomy has major implications for our understanding of the evolution of morphology, behavior and social organization for this clade. At present, I am working on an integration of the evidence for the evolutionary patterns in the New World Monkeys in light of the most recent molecular phylogeny of this group.