This article distinguishes preference aggregation, identity formation and the deliberation of norms as three functions performed by parliaments in systems of representative government. It argues that analysis of ‘what kind of parliament is the European Parliament (EP) in comparison to others?’ has hitherto focused excessively on preference aggregation to the exclusion of the other two elements. In seeking to correct this it reaches an original assessment of the three-way comparison that is often made between the EP, US Congress and national parliamentary systems of many EU Member States.