 An idea central to work on the psychology of norms is that human minds contain a norm system of some kind, a set of psychological mechanisms dedicated to handling information and producing behaviors relevant to norms. Such mechanisms feature in an explanatory strategy common throughout psychology (R. Cummins 2000). In this case, theorists appeal to different properties of the norm system to help account for different aspects of a complex capacity for norm-guided behavior—a capacity to “do” norms. This capacity is characterized by a broad but distinctive pattern of behavior: when faced with norm relevant stimuli, typically centered on other peoples’ actions or their own, along with other cues concerning the context of those actions and the roles of the actors, individuals exhibit a robust and multifaceted type of response that is centered on conformity and punishment. Taken together, the responses of individuals aggregate up to produce stabilizing group-level effects on patterns of collective social organization. The complexity and robustness of the individual capacity suggests the operation of dedicated psychological machinery—a norm system—which sensitizes humans to certain social stimuli (behavior, contexts, roles) and reliably produces the coordinated facets (physiologically, inferentially, behaviorally) of the characteristic response.