Four laws of party seats and votes are constructed by logic and tested, using physics-like approaches which are rare in social sciences.

1. Introduction: how electoral systems matter - for politics and for the scientific study thereof; Part I. Rules, Tools, and Context: 2. Components of simple electoral systems; 3. Components of complex and composite electoral systems; 4. The number of parties and proportionality - two key tools for analysis; 5. Examples of electoral systems: nationwide PR in Israel and FPTP in Trinidad and Tobago and India; 6. Two districted PR and list type: Finland, Portugal, and other cases; Part II. The Interparty Dimension of Assembly Politics: The Seat Product Model: 7. The seat product model of the effective number of assembly parties; 8. Winners plus one: how we get votes from seats; 9. Basic laws of party seats and votes - and application to deviation from proportionality; 10. All politics is national? How 'embeddedness' in a national assembly system shapes votes and seats in a district; Part III. Bringing the President In: 11. Coattails upside down: how assembly elections shape presidential elections; 12. How election timing matters in presidential democracy - and how it does not; Part IV. The Intraparty Dimension of Representation: 13. How electoral systems shape candidate vote shares; 14. Pooling or its absence: nomination and alliance behavior; Part V. What Can We Expect From Models of Electoral Systems?: 15. Extending the seat product model: upper tiers and ethnic diversity; 16. Complexities in electoral systems: do simple models work anyway? 17. Conclusion: substance and method.