The visual system takes advantage of redundancies in the scene by extracting summary statistics from a set of items. Similarly, in many social situations where scrutinizing each individual's expression is inefficient, human observers make snap judgments of crowds of people by reading "crowd emotion" to avoid danger (e.g., mass panic or violent mobs) or to seek help. However, how the brain accomplishes this feat remains unaddressed.Here we report a set of behavioral and fMRI studies in which participants made avoidance or approach decisions by choosing between two facial crowds presented in the left and right visual fields (LVF/RVF). Participants were most accurate for crowds containing task-relevant cues: avoiding angry crowds and approaching happy crowds.