A country's electoral system has a profound effect on its politics; its citizens ought therefore to ask themselves at frequent intervals whether that currently in force is satisfactory. This book does not argue for a particular answer, but aims to help people think about the question. Few realize how much thought it needs. One should not begin by asking whether this or that system is better, but by trying to make precise what we want an electoral system to do. A general election has two effects: it decides the composition of Parliament; and it decides who is going to represent each constituency. The question of what we want an electoral system to do therefore splits in two: how should Parliament be divided between the parties, given the voter's preferences? and which are the most representative local candidates, given the voter's preferences? Neither question is straightforward, but this timely new book helps to explain on what basis we should decide which electoral system we should have.