How do different electoral systems work to translate votes into seats? What effects do they have on the political system, on political actors, and on voters? Does the choice of electoral system always involve a trade-off between strong and stable government and representation? And do electoral systems matter as much as we might think? This fully revised and expanded third edition examines the principal types of electoral system used in over 75 of the world's democracies. It explores why countries choose the electoral systems they do, explains how the different systems function, and investigates their consequences, including on the party system and on government formation and stability, on representation and the quality of democracy, and on parties, politicians, and voters. Clearly structured, wide-ranging in focus, and incorporating of an array of visual material – including authentic ballot papers, tables and figures – this in-depth study remains the go-to text for students and researchers seeking to understand electoral systems around the world.