Even in brief or routine interactions, people constantly make judgments about others’ social worlds and their positions in social structure. These inferences matter in contexts as diverse as hiring, venture capital funding, and courtship encounters. Yet it remains unclear whether people are accurate in assessing the social networks in which others are embedded and, if so, which behavioral cues perceivers use to form these impressions. Drawing on the “thin-slicing” paradigm in social psychology and data on over 4,276 judgments made by 586 perceivers about 23 strangers, we find that people can accurately infer the size and composition of others’ networks. They are not, however, accurate in “seeing” the structure of relationships surrounding an individual.