The tamarins are squirrel-sized New World monkeys from the family Callitrichidae in the genus Saguinus. They are the first offshoot in the Callitrichidae tree, and therefore are the sister group of a clade formed by the lion tamarins, Goeldi's monkeys and marmosets.

New World monkeys are the five families of primates that are found in the tropical regions of Mexico, Central and South America: Callitrichidae, Cebidae, Aotidae, Pitheciidae, and Atelidae. The five families are ranked together as the Ceboidea, the only extant superfamily in the parvorder Platyrrhini.