The aim of this paper is to consider whether some seats in a democratically elected legislative assembly ought to be reserved for representatives of future generations. In order to examine this question, I will propose a new democratic model for representing posterity. It is argued that this model has several advantages compared with a model for the democratic representation of future people previously suggested by Andrew Dobson. Nevertheless, the democratic model that I propose confronts at least two difficult problems. First, it faces insoluble problems of representative legitimacy. Second, one might question whether this model provides a reasonably effective way to represent future interests compared with existing representative democratic institutions. Despite such problems, it is argued that political representation of posterity can be defended on the basis of fundamental ideas and ideals in recent theory of deliberative democracy. The first reason for this is that in a number of cases democratic decisions cannot be regarded as normatively legitimate from the point of view of deliberative democracy, unless posterity is given a voice. The second reason is that representation of posterity can contribute to more rational and impartial deliberations and decisions in legislative assemblies.