Our beliefs about one another’s political attitudes tend to be substantially mis-calibrated. This column analyses the factors shaping voters’ ideas about the political attitudes of other voters among the US electorate. Starting from the premise that individuals are not equally interested in all issues, it finds that when issue salience changes, beliefs about political groups can shift dramatically even when the underlying fundamentals remain the same. Meanwhile, the removal of a perceived external threat can induce citizens to perceive one another as further apart on domestic issues, undermining a country’s social cohesion.