'Scholars, pundits, and citizens spend an enormous amount of time trying to figure out why the political sides are so divided in contemporary American politics. In this provocative, path-breaking book, Krupnikov and Ryan offer a fundamental reorientation of what we know about polarization. They persuasively argue that the real divide in American politics is between the involved and the uninvolved. Moreover, the small number of involved citizens fundamentally differ from most Americans. This is true regarding their demographics, beliefs, levels of political polarization, parenting, how they express themselves, and how journalists cover them. These differences bisect the parties themselves. The book makes clear that involvement too is not a panacea for democracy, which requires all kinds of citizens and not just involved ones. This book sets the agenda for the next generation of work in American politics: do not dismiss or chastise the less engaged; instead, understand and value them.' James N. Druckman, Northwestern University