To be successful as a social animal, you need to know where you stand relative to others. Brain cells that perform precisely this function—locating the ‘self’ and others in space—have now been identified. In rats, the same brain area that stores the animal’s own location also maps the movements of other rats. Sometimes these representations are processed jointly by the same cells, depending on a rat’s goals and actions. This discovery, from Japan’s RIKEN Brain Science Institute, deepens our understanding of the hippocampus and its role as the brain’s positioning system.