We argue that the level of consensus about a set of social identity principles, and their perceived fundamentality, can influence the degree to which members perceive their group as an entity. This idea was explored through an experiment in which participants judged the entitativity of specific (in)groups on the basis of the distribution of the opinions held by their members about three identity-related principles that participants had previously rated for fundamentality. The results demonstrated that the more fundamental a principle was judged to be in comparison to other principles, the more important consensus about that principle was for producing group entitativity, relative to consensus about other principles. (PsycINFO Database Record (c) 2012 APA, all rights reserved) (journal abstract)