Daniel J. Hopkins is Associate Professor in the Department of Government at Georgetown University, USA. He contributes to The Monkey Cage and FiveThirtyEight.John Sides is Associate Professor in the Department of Political Science at George Washington University, USA. He is the co-author of The Gamble: Choice and Chance in the 2012 Presidential Election (2013). He contributes to The Monkey Cage.

This is a superb volume of thoughtful and wide-ranging essays on polarization by some of the best scholars in the political science field. If you want to learn about the causes, effects, and consequences of polarization in American politics and society, this should be your go-to source.

• PrefaceContributors1. What we know and don't know about our polarized politics-Nolan McCartyHow are we polarized?2. Partisan warfare is the problem-Sean Theriault3. How U.S. state legislatures are polarized and getting more polarized-Boris Shor4. Our politics is polarized on more issues than ever before-Thomas Carsey and Geoffrey Layman5. How politically moderate Americans? Less than it seems-Christopher Hare and Keith Poole6. Americans aren't polarized, just better sorted-Morris Fiorina and Samuel Abrams7. Are politicians and activists reliably 'more extreme' than voters? A skeptical perspective– David Broockman8. Party polarization is making us more prejudiced-Lilliana Mason9. Politics stops at the water's edge? Not recently-Robert LieberWhy are we polarized?10. The two key factors behind our polarized politics-Jeff Stonecash11. American politics is more competitive than ever, and that's making partisanship worse-Frances Lee12. How race and religion have polarized American voters-Alan Abramowitz13. How ideological activists constructed our polarized parties-Hans Noel14. How better educated whites are driving political polarization-Andrew Gelman15. Are Fox and MSNBC polarizing America?-Matthew Levendusky16. Why you shouldn't blame polarization on partisan news-Kevin Arceneaux17. The media make us think we're more polarized than we really are-Matthew Levendusky and Neil MalhotraPolarization Abroad18. Sure, Congress is polarized. But other legislatures are more so-David Brady19. Canada is polarizing-and it's because of the parties-Richard Johnston20. In Britain, polarization could be the solution-Rob FordWhat Can Be Done?21. Our politics may be polarized, but that's nothing new-David Brady and Hahrie Hahn22. Polarization in Congress has risen sharply. Where is it going next?-Christopher Hare, Keith Poole, and Howard Rosenthal23. Can young voters break the cycle of polarization?-Robert Shapiro24. How to fix our polarized politics? Strengthen political parties-Richard Pildes25. Our political parties are network, not fragmented-Seth Masket26. Gridlock is bad. The alternative is worse-Morris Fiorina