1. Introduction Nathaniel Persily 2. Causes and consequences of polarization Michael Barber and Nolan McCarty 3. Confronting asymmetric polarization Jacob Hacker and Paul Pierson Part I. Reforming the Electoral System: 4. Polarization and democratization Arend Lijphart 5. Eroding the electoral foundations of partisan polarization Gary C. Jacobson 6. Solutions to polarization Elaine C. Kamarck 7. Geography and gridlock in the United States Jonathan Rodden Part II. Strengthening Parties: 8. Parties as the solution to polarization Nathaniel Persily 9. Reducing polarization by making parties stronger Nolan McCarty 10. Focus on political fragmentation, not polarization: re-empower party leadership Richard H. Pildes 11. Two approaches to lessening the effects of partisanship Bruce Cain Part III. Empowering and Informing Moderate Voters: 12. Data science for the people Adam Bonica 13. Using mobilization, media, and motivation to curb political polarization Markus Prior and Natalie Jomini Stroud Part IV. Lowering Barriers to Policy Making: 14. Beyond confrontation and gridlock: making democracy work for the American people Alan I. Abramowitz 15. American political parties: exceptional no more David Karol 16. Partisan polarization and the Senate syndrome Steven S. Smith 17. Finding the center Russell Muirhead Part V. Fostering Negotiation: 18. Making deals in Congress Sarah A. Binder and Frances E. Lee 19. Helping Congress negotiate Jane Mansbridge 20. Staying private George C. Edwards, III.