Whether attending a business function or moving to a new neighborhood, the ability to recognize, remember, and garner information about the social relationships of other individuals is critical for human survival. But to what degree is this unique to humans? Nonhuman primates provide us with the opportunity to study the evolutionary history and function of human socio-cognitive skills within a comparative framework. I tested capuchin monkeys on three computerized tasks that evaluated their ability to discriminate the faces, sexual identities and dominance relationships of conspecifics living in their own social group, a neighboring social group or completely unfamiliar individuals. This paradigm allowed for testing the effect of familiarity and parsed underlying mechanisms of these socio-cognitive skills, both of which help to elucidate how social knowledge emerges from the foundations of perception.