Even in this most partisan and dysfunctional of eras, we can all agree on one thing: Washington is broken. Politicians take increasingly inflexible and extreme positions, leading to gridlock, partisan warfare, and the sense that our seats of government are nothing but cesspools of hypocrisy, childishness, and waste. The shocking reality, though, is that modern polarization was a deliberate project carried out by Democratic and Republican activists. In The Polarizers, Sam Rosenfeld details why bipartisanship was seen as a problem in the postwar period and how polarization was then cast as the solution. Republicans and Democrats feared that they were becoming too similar, and that a mushy consensus imperiled their agendas and even American democracy itself. Thus began a deliberate move to match ideology with party label—with the toxic results we now endure. Rosenfeld reveals the specific politicians, intellectuals, and operatives who worked together to heighten partisan discord, showing that our system today is not (solely) a product of gradual structural shifts but of deliberate actions motivated by specific agendas. Rosenfeld reveals that the story of Washington’s transformation is both significantly institutional and driven by grassroots influences on both the left and the right. The Polarizers brilliantly challenges and overturns our conventional narrative about partisanship, but perhaps most importantly, it points us toward a new consensus: if we deliberately created today’s dysfunctional environment, we can deliberately change it.